Therapeutic fusion proteins

ABSTRACT

The present invention relates to the construction of a new class of Targeted Secretion Inhibitors (TSIs), which comprise a non-cytotoxic protease, translocation peptide and a targeting moiety peptide, wherein the targeting moiety peptide has a free N-terminal domain and a free C-terminal domain; to a single-chain fusion protein precursor thereof, and to a method of activating said single-chain fusion protein precursor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 14/117,286, now U.S. Pat. No. 10,081,803, which is a U.S. national stage filing of International Patent Application No. PCT/GB2012/051104, filed on May 16, 2012, which claims the priority of United Kingdom Application No. 11081018.0, filed May 16, 2011.

REFERENCE TO SEQUENCE LISTING

The instant application contains a Sequence Listing that has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Nov. 13, 2018, is named 285623_ST25.txt and is 105,172 bytes in size.

BACKGROUND OF THE INVENTION

The present invention relates to the construction of a new class of Targeted Secretion Inhibitors (TSIs), to a method for the activation thereof, and to the activated product.

Non-cytotoxic proteases are a well-recognised group of proteases, which act on target cells by incapacitating cellular function. Importantly, non-cytotoxic proteases do not kill the target cells upon which they act. Some of the best known examples of non-cytotoxic proteases include clostridial neurotoxins (e.g. botulinum neurotoxin, which is marketed under names such as Dysport™, Neurobloc™, and Botox™) and IgA proteases.

Non-cytotoxic proteases act by proteolytically-cleaving intracellular transport proteins known as SNARE proteins (e.g. SNAP-25, VAMP, or Syntaxin)—see Gerald K (2002) “Cell and Molecular Biology” (4th edition) John Wiley & Sons, Inc. The acronym SNARE derives from the term Soluble NSF Attachment Receptor, where NSF means N-ethylmaleimide-Sensitive Factor. SNARE proteins are integral to intracellular vesicle formation, and thus to secretion of molecules via vesicle transport from a cell. Accordingly, once delivered to a desired target cell, the non-cytotoxic protease is capable of inhibiting cellular secretion from the target cell.

Non-cytotoxic proteases may be employed in their native or substantially native forms (i.e. as holotoxins, such as is the case with Dysport™, Neurobloc™, and Botox™), in which case targeting of the proteases to specific cell-types is reliant on (i) localised administration of the protease and/or (ii) the inherent binding ability of the native protease. Alternatively, non-cytotoxic proteases may be employed in a re-targeted form in which the native protease is modified to include an exogenous ligand known as a Targeting Moiety (TM). The TM is selected to provide binding specificity for a desired target cell, and, as part of the re-targeting process, the native binding portion of the non-cytotoxic protease may be removed.

The present Applicant has pioneered the concept and development of clostridial neurotoxin-based re-targeting technology, and the resulting fusion proteins are known as Targeted Secretion Inhibitors (TSIs).

TM replacement may be effected by conventional chemical conjugation techniques, which are well known to a skilled person. In this regard, reference is made to Hermanson, G. T. (1996), Bioconjugate techniques, Academic Press, and to Wong, S. S. (1991), Chemistry of protein conjugation and cross-linking, CRC Press.

Chemical conjugation is, however, often imprecise. For example, following conjugation, a TM may become joined to the remainder of the conjugate at more than one attachment site. Chemical conjugation is also difficult to control. For example, a TM may become joined to the remainder of the modified toxin at an attachment site on the protease component and/or on the translocation component. This is problematic when attachment to only one of said components (preferably at a single site) is desired for therapeutic efficacy. Thus, chemical conjugation results in a mixed population of modified toxin molecules, which is undesirable.

As an alternative to chemical conjugation, TM replacement may be effected by recombinant preparation of a single-chain polypeptide fusion protein. The preparation of such molecules is described in WO98/07864. However, the present inventors have identified that the WO98/07864 methodology is not suitable for all types of TM.

An alternative system to that of WO98/07864 is described in WO2006/059093. According to WO2006/059093, the TM is centrally-presented (CP) within the single-chain fusion protein, between the non-cytotoxic protease component and the translocation domain component. This results in a single-chain fusion protein having the following structure: NH₂-[protease component]-[TM]-[translocation component]-COOH

The above-described fusion proteins are activated by treatment with a protease, which cleaves at a site located at the C-terminus of the protease component. This activation process results in a di-chain protein comprising the protease component attached covalently (via a disulphide linkage) to the translocation component of the fusion protein. In the case of WO2006/059093, the resulting di-chain molecule has a TM that is peptide-bonded via its C-terminus to the N-terminus of the translocation domain component. Accordingly, the N-terminal portion of the TM is then free to interact and bind to a desired receptor. This arrangement is important for the class of TMs that requires a free N-terminus or a free N-terminal portion in order to bind to its receptor.

By way of example, following proteolytic activation, WO2006/059093 provides polypeptides having the following di-chain conformation:

In said di-chain conformation, the TM and translocation components are presented in the form of a single-chain fusion protein, wherein the C-terminus of the TM is peptide-bonded to the N-terminus of the translocation component.

The present inventors have found that the systems described in WO98/07864 and WO2006/059093 are not optimal for the presentation of all types of TM, and, as such, may result in the production of fusion proteins having undesirable/reduced binding ability for the intended target cell.

There is therefore a need for an alternative or improved system for constructing TSIs.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 Illustrates an SDS-PAGE analysis of activated samples (eluted in the 80 mM and 250 mM imidazole fractions) from Example 4 in reducing & non-reducing conditions.

DETAILED DESCRIPTION OF THE INVENTION

The present invention addresses one or more of the above-mentioned problems by providing a single-chain, polypeptide fusion protein, comprising:

(a) a non-cytotoxic protease or a fragment thereof, which protease or protease fragment is capable of cleaving a protein of the exocytic fusion apparatus of a target cell;

(b) a targeting moiety that is capable of binding to a binding site on the target cell, which binding site is capable of undergoing endocytosis to be incorporated into an endosome within the target cell;

(c) a translocation domain that is capable of translocating the protease or protease fragment from within an endosome, across the endosomal membrane and into the cytosol of the target cell;

(d) a first protease cleavage site at which site the fusion protein is cleavable by a first protease, wherein the first protease cleavage site is located between the non-cytotoxic protease and the translocation domain;

(e) a second protease cleavage site at which site the fusion protein is cleavable by a second protease, wherein the second protease cleavage site is located between the translocation domain and the targeting moiety; and

(f) a covalent linkage between the targeting moiety and the translocation domain, wherein following proteolytic cleavage at the second protease cleavage site the targeting moiety remains linked to the translocation domain by said covalent linkage.

The system described in WO2006/059093 provides TSIs having a TM with an N-terminus that is free to interact with a binding site on a target cell. However, the present inventors have found that the system described in WO2006/059093 is not suitable for TMs that require both a free N-terminal domain and a free C-terminal domain in order to interact with a binding site on a target cell.

Thus, in contrast to WO2006/059093, the present invention provides a system for providing TSIs wherein the TM component has both a free N-terminal domain and a free C-terminal domain.

In one embodiment, the present invention provides a single-chain fusion protein having the following N-terminus to C-terminus orientation, wherein P1 and P2 represent the first and second protease cleavage sites: NH₂-[protease component]-[P1]-[TM]-[P2]-[translocation component]-COOH

Following cleavage at the first and second cleavage sites, said single-chain fusion protein assumes the following tri-chain structure in which the TM and translocation components are covalently linked together, and wherein

A) the protease component is covalently linked to the TM component:

or B) the protease component is covalently linked to the translocation component:

In another embodiment, the present invention provides a single-chain fusion protein having the following N-terminus to C-terminus orientation, wherein P1 and P2 represent the first and second protease cleavage sites: NH₂-[protease component]-[P1]-[translocation component]-[P2]-[TM]-COOH

Following cleavage at the first and second cleavage sites, said single-chain fusion protein assumes the following tri-chain structure in which the TM and translocation components are covalently linked together, and wherein

A) the protease component is covalently linked to the translocation component:

or B) the protease component is covalently linked to the TM component:

In another embodiment, the present invention provides a single-chain fusion protein having the following N-terminus to C-terminus orientation, wherein P1 and P2 represent the first and second protease cleavage sites: NH₂-[TM]-[P2]-[protease component]-[P1]-[translocation component]-COOH

Following cleavage at the first and second cleavage sites, said single-chain fusion protein assumes the following tri-chain structure in which the TM and translocation components are covalently linked together, and wherein

A) the protease component is covalently linked to the translocation component:

or B) the protease component is covalently linked to the TM component:

In use, a polypeptide TSI of the present invention binds to a target cell, the binding being facilitated by the TM. The translocation domain component then effects transport of the non-cytotoxic protease component into the cytosol of the target cell. Once inside, the non-cytotoxic protease component inhibits the exocytic fusion process of the target cell. Thus, by inactivating the exocytic fusion apparatus of the target cell, the polypeptide of the present invention inhibits secretion therefrom. Accordingly, the TSI polypeptides of the present invention can be used to suppress or treat a variety of pathophysiological conditions or symptoms that are linked to cellular secretion.

The Non-Cytotoxic Protease

The biologically active component of the TSI polypeptides of the present invention is a non-cytotoxic protease. Thus, once delivered into the cytosol of a target cell, the non-cytotoxic protease component effects SNARE cleavage within the desired target cell. Since SNARE proteins are an essential component of the secretory process within mammalian target cells, proteolytic inactivation thereof inhibits/suppresses secretion from said target cells.

Non-cytotoxic proteases are a discrete class of molecules that do not kill cells; instead, they act by inhibiting cellular processes other than protein synthesis. Non-cytotoxic proteases are produced by a variety of higher organisms (e.g. plants, and animals)—an example of such a higher organism is the Brazilian scorpion. In addition, non-cytotoxic proteases are produced by a variety of microorganisms, notably bacteria such as Clostridium sp. and Neisseria sp.

Clostridial neurotoxins represent a major group of non-cytotoxic toxin molecules, and comprise two polypeptide chains joined together by a disulphide bond. The two chains are termed the heavy chain (H-chain), which has a molecular mass of approximately 100 kDa, and the light chain (L-chain), which has a molecular mass of approximately 50 kDa. It is the L-chain, which possesses a protease function and exhibits high substrate specificity for vesicle and/or plasma membrane associated (SNARE) proteins involved in the exocytic process (e.g. synaptobrevin, syntaxin, SNAP and/or VAMP). These substrates are important components of a cell's secretory machinery.

Neisseria sp., most notably from the species N. gonorrhoeae, produce functionally similar non-cytotoxic toxin molecules. An example of such a non-cytotoxic protease is IgA protease (see WO99/58571). Similar IgA proteases are produced by streptococci, such as Streptococcus pneumoniae.

Thus, in one embodiment the non-cytotoxic protease of the present invention may be a clostridial neurotoxin protease or an IgA protease (see, for example, WO 99/032272). Another example of non-cytotoxic proteases is a scorpion venom protease, such as those from the venom of the Brazilian scorpion Tityus serrulatus, or the protease antarease (see, for example, WO 2011/022357).

The Targeting Moiety (TM)

The TM component of the present invention is responsible for binding the polypeptide of the present invention to a Binding Site on a target cell. Thus, the TM component is a ligand through which a polypeptide of the present invention binds to a selected target cell.

In the context of the present invention, the target cell may be any mammalian (preferably human) cell. Thus, the TM may bind to a non-neuronal cell and/or to a neuronal cell.

The TM component of the polypeptides of the present invention has both a free N-terminal portion and a free C-terminal portion. Thus, in one embodiment, the TM is capable of interacting with the binding site (e.g. a receptor or acceptor) on a target cell via an interaction between an N-terminal portion of the targeting moiety and a domain of the binding site. In another embodiment, the TM is capable of an interaction between the C-terminal portion of the targeting moiety and a domain of a binding site. In another embodiment, the TM is capable of a dual interaction, wherein an N-terminal portion of the targeting moiety interacts with a domain of the binding site and a C-terminal portion of the targeting moiety interacts with a domain of a binding site. In this latter embodiment, the N- and C-terminal portions of the TM may bind to the same or different domains of a binding site, and/or may bind to domains on different binding sites.

Suitable TMs for use in the polypeptides of the present invention include cytokines, growth factors, neuropeptides, lectins, and antibodies—this term includes monoclonal antibodies, protein binding scaffolds, antibody fragments such as Fab, F(ab)′₂, Fv, ScFv, and single-chain antibodies such as camelids etc.

In one embodiment, the TM component comprises or consists of a peptide ligand (e.g. a peptide hormone) that binds to a receptor present on a target cell. In one embodiment, the peptide ligand has an amino acid sequence of 5-200 consecutive amino acid residues. By way of example, said peptide ligand consists or comprises an amino acid sequence of 5-150 or 5-100 or 5-50 or 5-40 or 5-30 or 5-25 or 5-20 or 7-12 or approximately 10 consecutive amino acid residues.

The TM component comprises an N-terminal portion and a C-terminal portion. Each of said portions typically comprise at least 5, at least 10, at least 15, at least 20, or at least 25 consecutive amino acid residues.

In one embodiment, the TM comprises or consists of a peptide ligand (or an analogue thereof) that binds to a receptor selected from MRGPRX₁ (e.g. a Bovine Adrenal Medulla (BAM) peptide receptor), an opioid peptide receptor, OPRM₁ or OPRID₁ (e.g. a beta-endorphin peptide receptor), BDKRIB₁ or BDKRB₂ (e.g. a bradykinin peptide receptor), OPRM1 or OPRD1 (e.g. a met- or leu-enkephalin peptide receptor), OPRK₁ (e.g. a dynorphin peptide receptor), GALR₁, GALR₂ or GALR₃ (e.g. a galanin peptide receptor), OPRL₁ (e.g. a nociceptin peptide receptor), and TACR₁, TACR₂ or TACR₃ (e.g. a substance P peptide receptor).

In one embodiment, the TM comprises or consists of a peptide ligand (or an analogue thereof) selected from a Bovine Adrenal Medulla (BAM) peptide, an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, a met- or leu-enkephalin peptide, a dynorphin peptide, a galanin peptide, a nociceptin peptide, and a substance P peptide.

In one embodiment, the TM comprises or consists of a gonadotropin-releasing hormone (GnRH) peptide. GnRH is a 10 amino acid peptide hormone. The N-terminal amino acids of GnRH have a role in receptor activation while the C-terminal amino acids are required for high affinity binding to the GnRH receptor (see Flanagan, Millar & IIling (1997) Reviews of Reproduction, 2, 113-120, which is hereby incorporated in its entirety by reference thereto). The function of GnRH in vivo is to act on GnRH receptors located on the anterior pituitary gland and to stimulate the synthesis and release of gonadotropins, such as luteinising hormone (LH) and follicle-stimulating hormone (FSH). Reference to GnRH peptide embraces all functional binding fragments, variants and analogues thereof. By way of example, the term GnRH peptide embraces a GnRH peptide into which a cysteine amino acid (flanked by two achiral amino acid residues such as glycine and/or alanine) has been inserted as a replacement amino acid for position 6 of the GnRH peptide. GnRH is also known as Luteinizing-Hormone Releasing Hormone (LHRH). Further examples include GnRHI peptides, GnRHII peptides and GnRHIII peptides, as well as the full-length 92 amino acid GnRH precursor polypeptide and truncations thereof.

In one embodiment, the TM comprises or consists of a corticotrophin-releasing factor (CRF) peptide. CRF is a 41 amino acid hypothalamic peptide hormone that interacts with CRF, and CRF₂ receptors. The main function of CRF in vivo is to stimulate the release of ACTH from the corticotropes within the anterior lobe of the pituitary.

Reference to CRF peptide embraces full-length CRF, urocortin 1 and urocortin 2, as well as all functional binding fragments, variants and analogues thereof.

In one embodiment, the TM comprises or consists of a gastrin releasing peptide (GRP). GRP is a 27 amino acid peptide hormone. GRP regulates numerous functions of the gastrointestinal and central nervous systems, including release of gastrointestinal hormones, smooth muscle cell contraction, and epithelial cell proliferation and is a potent mitogen for neoplastic tissues. Reference to GRP peptide embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, the TM comprises or consists of a neuromedin B. Neuromedin B is a 10 amino acid peptide hormone. The function of neuromedin B acts on BB, receptors in vivo and is a potent mitogen and growth factor for normal and neoplastic lung and for gastrointestinal epithelial tissue. Reference to neuromedin B peptide embraces all functional binding fragments, variants and analogues thereof. Reference to Neuromedin B embraces the human homolog peptide, bombesin, and includes full-length: bombesin—a 14 amino acid peptide originally isolated from the skin of a frog—as wells as truncations and peptide analogues thereof.

In one embodiment, the TM comprises or consists of gastrin or cholecystokinin (CCK). Gastrin is a 17 amino acid peptide hormone, CCK is a 8 amino acid peptide hormone. Both gastrin and cholecystokinin act on CCK1 and CCK2 receptors in vivo primarily within the gastrointestinal system and CNS to modulate pancreatic enzyme secretion and smooth muscle contraction of the gallbladder and stomach, anxiety, analgesia, arousal, and neuroleptic activity. Reference to gastrin and cholecystokinin peptides embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, a TM comprises or consists of a somatostatin (SST) peptide. Examples of suitable SST peptide TMs include full-length SST and cortistatin (CST), as well as truncations and peptide analogues thereof such as BIM 23052, BIM 23056 or BIM23268; octreotide peptides, lanreotide peptides, BIM23027, CYN154806, BIM23027, vapreotide peptides, seglitide peptides, and SOM230. These TMs bind to sst receptors, such as sst₁, sst₂, sst₃, sst₄ and sst₅ receptors. SST and CST have high structural homology, and bind to all known sst receptors. Reference to SST or CST peptides embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, a TM comprises or consists of a growth hormone releasing hormone (GHRH) peptide. GHRH is also known as growth-hormone-releasing factor (GRF or GHRF) or somatocrinin. Suitable GHRH peptides include full-length GHRH (1-44) peptide, and truncations thereof such as GHRH (1-27, 1-28, 1-29), GHRH (1-37), and GHRH (1-40, 1-43)-OH, as well as peptide analogues such as BIM 28011 or NC-9-96. Reference to GHRH peptide embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, a TM comprises or consists of a proteinase activated receptor (PAR) peptide, for example PAR1. PAR peptides represent a unique subtype of 7-transmembrane receptor G-protein-coupled receptors in that they are proteolytically modified to expose a new extracellular N-terminus, which acts as a tethered activating ligand. PAR1 agonists (such as TFLLR) have been identified that activate their cognate receptor. Reference to PAR peptide embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, a TM comprises or consists of a parathyroid hormone (PTH). PTH is a peptide that is released by the parathyroid gland and binds to the PTH-1 receptor. This receptor has a widespread distribution but is particularly abundant in PTH target tissues, predominantly the kidney and in bone. Reference to PTH peptide embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, a TM comprises or consists of a peptide that binds to a mucus-secreting cell, or to a neuronal cell controlling or directing mucus secretion. For example, the TM binds to (a) cells that secrete mucins, such as epithelial goblet cells and submucosal gland mucus secreting cells, (b) cells that secrete aqueous components of mucus, such as Clara cells and serous cells, and/or (c) cells that control or direct mucus secretion, such as “sensory-efferent” C-fibres, or NANC neural system fibres. Particular mention is made to the following peptide TMs: VIP; beta₂ adrenoreceptor agonists; gastrin-releasing peptide; and calcitonin gene related peptide. Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application in treating mucus hypersecretion, asthma, and/or chronic obstructive pulmonary disease.

In another embodiment, the TM comprises or consists of a peptide that binds to an endocrine cell. Particular mention is made here to GHRH; thyroid stimulating hormone (TSH); insulin, insulin-like growth factor; TSH releasing hormone (protirelin); FSH/LH releasing hormone (gonadorelin); corticotrophin releasing hormone (CRH); and ACTH. Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application in treating: endocrine neoplasia including MEN; thyrotoxicosis and other diseases dependent on hypersecretions from the thyroid; acromegaly, hyperprolactinaemia, Cushings disease and other diseases dependent on anterior pituitary hypersecretion; hyperandrogenism, chronic anovulation and other diseases associated with polycystic ovarian syndrome.

In another embodiment the TM comprises or consists of a peptide that binds to an inflammatory cell. Particular mention here is made to peptide TMs (i) for mast cells, such as the C4 domain of the Fc IgE; (ii) for eosinophils, such as ligands to the C3a/C4a-R complement receptor, antigens reactive towards CR4 complement receptor; (iii) for macrophages and monocytes, such as macrophage stimulating factor, (iv) for neutrophils, such as an antigen associated with the iC3b complement receptor, or IL8. Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application for treating allergies (seasonal allergic rhinitis (hay fever), allergic conjunctivitis, vasomotor rhinitis and food allergy), eosinophilia, asthma, rheumatoid arthritis, systemic lupus erythematosus, discoid lupus erythematosus, ulcerative colitis, Crohn's disease, haemorrhoids, pruritus, glomerulonephritis, hepatitis, pancreatitis, gastritis, vasculitis, myocarditis, psoriasis, eczema, chronic radiation-induced fibrosis, lung scarring and other fibrotic disorders.

In another embodiment, the TM comprises or consists of a peptide that binds to an exocrine cell. Particular mention here is made to pituitary adenyl cyclase activating peptide (PACAP-38). Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application for treating mucus hypersecretion from mucus-secreting cells located in the alimentary tract, in particular located in the colon.

In a further embodiment, the TM comprises or consists of a peptide that binds to an immunological cell. Mention here is made to the ligands such as Epstein Barr virus fragment/surface feature. Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment, have therapeutic application for treating myasthenia gravis, rheumatoid arthritis, systemic lupus erythematosus, discoid lupus erythematosus, organ transplant, tissue transplant, fluid transplant, Graves disease, thyrotoxicosis, autoimmune diabetes, haemolytic anaemia, thrombocytopenic purpura, neutropenia, chronic autoimmune hepatitis, autoimmune gastritis, pernicious anaemia, Hashimoto's thyroiditis, Addison's disease, Sjogren's syndrome, primary biliary cirrhosis, polymyositis, scleroderma, systemic sclerosis, pemphigus vulgaris, bullous pemphigoid, myocarditis, rheumatic carditis, glomerulonephritis (Goodpasture type), uveitis, orchitis, ulcerative colitis, vasculitis, atrophic gastritis, pernicious anaemia, type 1 diabetes mellitus.

In a further embodiment the TM comprises or consists of a peptide that binds to a cardiovascular cell. Mention here is made to thrombin and TRAP (thrombin receptor agonist peptide), and ligands that bind to cardiovascular endothelial cells such as GP1b surface antigen-recognising antibodies. Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application for treating cardiovascular conditions and/or hypertension

In a further embodiment, the TM comprises or consists of a peptide that binds to a bone cell. Mention here is made to ligands that bind to osteoblasts for the treatment of a disease selected from osteopetrosis and osteoporosis include calcitonin, and to ligands that bind to osteoclasts including osteoclast differentiation factors (e.g. TRANCE, or RANKL or OPGL). Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof. Thus, TSIs according to this embodiment have therapeutic application for treating bone conditions.

Linear and cyclic integrin binding sequences represent a further group of peptide TMs of the present invention. Many integrins recognise the triple Arg-Gly-Asp (RGD) peptide sequence (Ruoslahti, 1996). The RGD motif is found in over 100 proteins including fibronectin, tenascin, fibrinogen and vitronectin. The RGD-integrin interaction is exploited as a conserved mechanism of cell entry by many pathogens including coxsackievirus (Roivaninen et al., 1991) and adenovirus (Mathias et al., 1994). The linear and cyclic peptide sequences, PLAEIDGIEL (SEQ ID NO: 17) and CPLAEIDGIELC (SEQ ID NO: 18) respectively, have been shown to bind and internalise DNA in cells expressing α₉β₁ integrin (Schneider et al., 1999). Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof.

Other TMs of the present invention include those discovered by phage display techniques, in particular those which target and are internalised by human airway epithelial cells. These include, linear and cyclic THALWHT (SEQ ID NO: 19) (Jost et al., 2001); LEBP-1 (QPFMQCLCLIYDASC) (SEQ ID NO: 20), LEBP-2 (RNVPPIFNDVYWIAF) (SEQ ID NO: 21) and LEBP-3 (VFRVRPWYQSTSQS) (SEQ ID NO: 22) (Wu et al., 2003); CDSAFVTVDWGRSMSLC (SEQ ID NO: 23) (Florea et al., 2003); SERSMNF (SEQ ID NO: 24), YGLPHKF (SEQ ID NO: 25), PSGAARA (SEQ ID NO: 26), LPHKSMP (SEQ ID NO: 27), LQHKSMP (SEQ ID NO: 28) (Writer et al., 2004); FSLSKPP (SEQ ID NO: 29), HSMQLST (SEQ ID NO: 30) and STQAMFQ (SEQ ID NO: 31) peptides (Rahim et al., 2003). Reference to these peptide TMs embraces all functional binding fragments, variants and analogues thereof.

In one embodiment, the TM comprises or consists of first and second portions (e.g. domains). In one embodiment, the first and second portions of the targeting moiety may be derived from the same ligand (e.g. any of the above-identified TM ligands). The first and second portions may bind to the same of different sites on the same receptor. Alternatively, the first and second portions may bind sites on different receptors.

The first and second portions of the targeting moiety may be derived from different ligands (e.g. any of the above-identified TM ligands), which may bind to the same or to different receptors. Accordingly, the TM may be a hybrid of two TMs. The first and second portions may bind to the same of different sites on the same receptor. Alternatively, the first and second portions may bind sites on different receptors.

The TM may further include third and/or subsequent portions from yet further TMs (e.g. any of the above-identified TM ligands).

In one embodiment, the first portion (e.g. domain) comprises or consists of a ligand that binds via a free N-terminal portion (e.g. a free N-terminus) to its target receptor. An example of such a ligand is a ligand that binds to an opioid receptor (e.g. a ligand that binds to an ORL₁ receptor, such as an opioid peptide). Further examples of opioid peptides include nociceptin, dynorphin, beta-endorphin, and enkephalin. Other non-opioid peptide TM ligands include BAM, galanin, substance P, GnRH, CRF, GRP, Neuromedin B, bombesin, gastrin, CCK, SST, CST, and GHRH peptides (as well as truncations, variants and analogues thereof).

In another (or the same) embodiment, the second portion (e.g. domain) comprises or consists of a ligand that binds via a free C-terminal portion (e.g. a free C-terminus) to its target receptor. An example of such a ligand is a ligand that binds to a bradykinin receptor (e.g. a bradykinin peptide) or to a substance P receptor (e.g. a substance P peptide). Other peptide TM ligands include BAM, galanin, substance P, GnRH, CRF, GRP, Neuromedin B, bombesin, gastrin, CCK, SST, CST, and GHRH peptides (as well as truncations, variants and analogues thereof).

By way of example, the hybrid TM includes a first portion that comprises or consists of a nociceptin peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of a nociceptin peptide and the second portion comprises or consists of a peptide selected from a BAM peptide, an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, an enkephalin peptide, a dynorphin peptide, a galanin peptide, and a substance P peptide.

In another example, the hybrid TM includes a first portion that comprises or consists of a dynorphin peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of a dynorphin peptide and the second portion comprises or consists of a peptide selected from a BAM peptide, an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, an enkephalin peptide, a nociceptin peptide, a galanin peptide, and a substance P peptide.

In another example, the hybrid TM includes a first portion that comprises or consists of a galanin peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of a galanin peptide and the second portion comprises or consists of a peptide selected from a BAM peptide, an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, an enkephalin peptide, a nociceptin peptide, a dynorphin peptide, and a substance P peptide.

In another example, the hybrid TM includes a first portion that comprises or consists of a BAM peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of a BAM peptide and the second portion comprises or consists of a peptide selected from an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, an enkephalin peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, and a substance P peptide.

In another example, the hybrid TM includes a first portion that comprises or consists of a beta-endorphin peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of a beta-endorphin peptide and the second portion comprises or consists of a peptide selected from an opioid peptide, a BAM peptide, a bradykinin peptide, an enkephalin peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, and a substance P peptide.

In another example, the hybrid TM includes a first portion that comprises or consists of an enkephalin (e.g. leu- or met-enkephalin) peptide and a second portion that comprises or consists of a bradykinin peptide (or a substance P peptide). In further examples, the first portion comprises or consists of an enkephalin peptide and the second portion comprises or consists of a peptide selected from an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, a BAM peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, and a substance P peptide.

In one embodiment, the TM comprises or consists of first and second portions (e.g. domains) that are identical (or similar) and, in combination, provide efficacious interaction with the receptor on the target cell. Further (e.g. third, and optionally additional etc) identical/similar portions may also be included. Thus, in this embodiment, the polypeptides of the present invention comprise a repeating structure (e.g. TM-TM; TM-TM-TM etc) of the same (or a similar) TM.

Examples of such repeating TM structures (e.g. TM-TM; TM-TM-TM; etc) are provided by a TM selected from an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, a BAM peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, an enkephalin peptide, a substance P peptide, a GnRH peptide, a CRF peptide, a GRP peptide, a Neuromedin B peptide, a bombesin peptide, a gastrin peptide, a CCK peptide, a SST peptide, a CST peptide, and a GHRH peptide (as well as truncations, variants and analogues thereof).

In one embodiment, the first and second (and/or subsequent) portions of the TM are separated by a spacer sequence, for example a peptide sequence. In one embodiment, the first and second (and/or subsequent) portions may be separated by a sequence of at most 40 or at most 35 or at most 30 or at most 25 or at most 20 or at most 15 or at most 10 at most 5 amino acid residues. In one embodiment, the first and second (and/or subsequent) portions may be separated by a sequence of 4, 3, 2, 1 or zero amino acid residues.

The fusion proteins of the present invention generally demonstrate a reduced binding affinity (in the region of up to 100-fold) for target cells when compared with the corresponding ‘free’ TM (i.e. the isolated TM per se). However, despite this observation, the fusion proteins of the present invention surprisingly demonstrate good efficacy. This can be attributed to two principal features. First, the non-cytotoxic protease component is catalytic—thus, the therapeutic effect of a few such molecules is rapidly amplified within a target cell. Secondly, the receptors present on the target cells need only act as a gateway for entry of the therapeutic, and need not necessarily be stimulated to a level required in order to achieve a ligand-receptor mediated pharmacological response. Accordingly, the fusion proteins of the present invention may be administered at a dosage that is lower than would be employed for other types of therapeutic molecules, which are typically administered at high microgram to milligram (even up to hundreds of milligram) quantities. In contrast, the fusion proteins of the present invention may be administered at much lower dosages, typically at least 10-fold lower, and more typically at 100-fold lower.

The Translocation Domain

The translocation component of the present invention enables translocation of the non-cytotoxic protease (or fragment thereof) into the target cell so that functional expression of protease activity occurs within the cytosol of the target cell. The translocation component is preferably capable of forming ion-permeable pores in lipid membranes (e.g. endosomal membranes) under conditions of low pH. The translocation component may be obtained from a microbial protein source, for example a bacterial or viral protein source. Hence, in one embodiment, the translocation component comprises or consists or a translocation domain of an enzyme, such as a bacterial toxin. In another embodiment, the translocation domain comprises or consists of the translocation domain of a viral protein. In one embodiment, the translocation component of the present invention may comprise or consist of a clostridial neurotoxin H-chain or a fragment thereof such as the H_(N) domain (or a translocating fragment thereof) of a clostridial neurotoxin.

The First and Second Protease Cleavage Sites

The polypeptides of the present invention comprise a first protease cleavage site. The first protease cleavage site allows cleavage (e.g. controlled cleavage) of the fusion protein at a position between the non-cytotoxic protease component and the remainder of the fusion protein. This cleavage event serves to ‘activate’ the single-chain (non-cytotoxic protease-translocation domain) structure, and results in the formation of an ‘activated’ di-chain structure in which the non-cytotoxic protease component is covalently linked (e.g. disulphide-bonded) to the remainder of the fusion protein.

The polypeptides of the present invention also comprise a second protease cleavage site. The second protease cleavage site allows cleavage (e.g. controlled cleavage) of the fusion protein at a position between the targeting moiety component and the translocation domain component. This cleavage event serves to separate the single-chain (TM-translocation domain) structure, and results in the formation of a separate di-chain structure in which the TM component is covalently linked (e.g. disulphide-bonded) to the translocation component of the fusion protein. In doing so, the structural environment of the TM component is changed such that it becomes presented in a conformation in which both the N-terminal and C-terminal portions (e.g. domains) are no longer peptide-bonded to the remainder of the fusion protein and are thus each able freely to interact with (e.g. bind to) different binding domains on one (or more) receptor.

Thus, proteolytic cleavage at either the first or second protease cleavage sites converts the single-chain polypeptide fusion protein into a di-chain polypeptide. In the case of a cleavage reaction at the first protease cleavage site, the non-cytotoxic protease component remains linked by a covalent linkage (e.g. a disulphide bond) to the translocation domain component and/or to the TM component. Said covalent linkage may be indirect, for example, via one (or more) spacer or linker molecule, which is itself linked to the non-cytotoxic protease component, the TM component and/or the translocation component. Similarly, in the case of a cleavage reaction at the second protease cleavage site, the translocation domain component remains linked to the TM component by a covalent linkage (e.g. a disulphide bond). Said covalent linkage may be indirect, for example, via one (or more) spacer or linker molecule, which is itself linked to the translocation component and/or the TM.

Where cleavage reactions occur at both the first and second protease cleavage sites, the single-chain polypeptide fusion protein is converted into a tri-chain polypeptide.

The first and second protease cleavage sites may be introduced (and/or any inherent cleavage sequence removed) at the DNA level by conventional means, such as by site-directed mutagenesis. Screening to confirm the presence of cleavage sequences may be performed manually or with the assistance of computer software (e.g. the MapDraw program by DNASTAR, Inc.).

Whilst any protease cleavage site may be employed for use as the first protease cleavage site and/or for use as the second protease cleavage site in the polypeptides of the present invention, the following are preferred:

Enterokinase (DDDDK↓ (SEQ ID NO: 32)) Factor Xa (IEGR↓ (SEQ ID NO: 33)/ IDGR↓ (SEQ ID NO: 34)) TEV (Tobacco (ENLYFQ↓G (SEQ ID NO: 35)) Etch virus) Thrombin (LVPR↓GS (SEQ ID NO: 36)) PreScission (LEVLFQ↓GP (SEQ ID NO: 37))

Further non-limiting examples include plant papain cleavage site, and insect papain cleavage site, a crustacean papain cleavage site, a human rhinovirus 3C protease cleavage site, a human enterovirus 3C protease cleavage site, a tobacco etch virus (TEV) protease cleavage site, a Tobacco Vein Mottling Virus (TVMV) cleavage site, a subtilisin cleavage site, a hydroxylamine cleavage site, or a Caspase 3 cleavage site.

Also embraced by the term protease cleavage site is an intein, which is a self-cleaving sequence. The self-splicing reaction is controllable, for example by varying the concentration of reducing agent present. Also embraced by the term protease cleavage site is the cleavage sequence upon which a non-cytotoxic protease (e.g. a clostridial neurotoxin) acts. An example of such a cleavage site is a SNARE protein cleavage site sequence—examples of the native cleavage site recognition sequences for a range of non-cytotoxic proteases are provided towards the end of the present description section.

The first and second cleavage site may be the same or different. The first and second cleavage sites may be cleaved by (only) the same or (only) by different proteases.

As a separate aspect of the present invention, the above-mentioned cleavage sites/cleaving protease may be separately employed as a “destructive” cleavage site/protease (discussed below) should one be incorporated into a polypeptide of the present invention.

In one embodiment, in the single-chain polypeptide, the non-cytotoxic protease component and the translocation domain component are linked together by a disulphide bond. Thus, following cleavage of the first protease cleavage site, the polypeptide assumes a di-chain conformation, wherein the protease and translocation components remain linked together by the disulphide bond. This cleavage reaction is generally referred to as the “activation” step as it results in the non-cytotoxic protease component having increased (e.g. optimal) protease activity.

In one embodiment, the non-cytotoxic protease component forms a covalent bond with the translocation domain component of the fusion protein. For example, in one embodiment the amino acid residue of the protease component that forms the covalent bond is located within the last 20, preferably within the last 10 C-terminal amino acid residues of the protease component. Similarly, in one embodiment the amino acid residue within the translocation component that forms the second part of the covalent bond may be located within the first 20, preferably within the first 10 N-terminal amino acid residues of the translocation component.

The above covalent bond arrangements have the advantage that the protease and translocation components are arranged in a manner similar to that for a native non-cytotoxic protease (e.g. a native clostridial neurotoxin). By way of comparison, referring to the primary amino acid sequence for native clostridial neurotoxin, the respective cysteine amino acid residues are distanced apart by between 8 and 27 amino acid residues—taken from Popoff, M R & Marvaud, J-C, 1999, Structural & genomic features of clostridial neurotoxins, Chapter 9, in The Comprehensive Sourcebook of Bacterial Protein Toxins. Ed. Alouf & Freer:

‘Native’ length Serotype¹ Sequence between C-C BoNT/A1 CVRGIITSKTKS----LDKGYNKALNDLC 23 (SEQ ID NO: 38) BoNT/A2 CVRGIIPFKTKS----LDEGYNKALNDLC 23 (SEQ ID NO: 39) BoNT/B CKSVKAPG-------------------IC  8 (SEQ ID NO: 40) BoNT/C CHKAIDGRS----------LYNKTLDC 15 (SEQ ID NO: 41) BoNT/D CLRLTK---------------NSRDDSTC 12 (SEQ ID NO: 42) BoNT/E CKN-IVSVK----------GIRK---SIC 13 (SEQ ID NO: 43) BoNT/F CKS-VIPRK----------GTKAPP-RLC 15 (SEQ ID NO: 44) BoNT/G CKPVMYKNT----------GKSE----QC 13 (SEQ ID NO: 45) TeNT CKKIIPPTNIRENLYNRTASLTDLGGELC 27 (SEQ ID NO: 46) ¹Information from proteolytic strains only

In one embodiment, the non-cytotoxic protease component and the first protease cleavage site component of a single-chain fusion protein of the present invention are separated by at most 30, 25, 20, 15 or 10 amino acid residues. In one embodiment, said two components are separated within the single-chain fusion protein by at most 5, 4, 3, 2 or 1 amino acid residues. In another embodiment, said two components are separated within the single-chain fusion protein by zero amino acid residues.

Thus, in one embodiment, the non-cytotoxic protease and the first protease cleavage site may be separated using a first spacer sequence, said spacer sequence being located N-terminal to the first protease cleavage site and C-terminal of the non-cytotoxic protease component. In one embodiment, the first spacer sequence may comprise part or all of the first protease cleavage site, or may be part of the non-cytotoxic protease component.

In one embodiment, the translocation domain (or TM) component and the first protease cleavage site component of the single-chain fusion protein are separated by at most 30, 25, 20, 15 or 10 amino acid residues. In one embodiment, said two components are separated within the single-chain fusion protein by at most 5, 4, 3, 2 or 1 amino acid residues. In another embodiment, said two components are separated within the single-chain fusion protein by zero amino acid residues.

Thus, in one embodiment, the translocation domain (or TM) and the first protease cleavage site may be separated by a second spacer sequence, said second spacer sequence being located C-terminal to the first protease cleavage site and N-terminal of the translocation domain (or TM) component. The second spacer sequence may be identical to or different from the first spacer sequence separating the non-cytotoxic protease and the first protease cleavage site. In one embodiment, the second spacer sequence may comprise part or all of the second protease cleavage site, or may be part of the translocation domain component.

In one embodiment, the translocation domain component and the second protease cleavage site component of the single-chain fusion protein are separated at most 30, 25, 20, 15 or 10 amino acid residues. In one embodiment, said two components are separated within the single-chain fusion protein by at most 5, 4, 3, 2 or 1 amino acid residues. In another embodiment, said two components are separated within the single-chain fusion protein by zero amino acid residues.

Thus, in one embodiment, the translocation domain and the second protease cleavage site may be separated by a third spacer sequence, said third spacer sequence being located N-terminal or C-terminal to the translocation domain. The third spacer sequence may be identical to (or different from) one or both of the first and second spacer sequences. In one embodiment, the third spacer sequence may comprise part or all of the second protease cleavage site, or may be part of the translocation domain component.

In one embodiment, the targeting moiety and the second protease cleavage site are separated by at most 30, 25, 20, 15 or 10 amino acid residues. In one embodiment, said two components are separated within the single-chain fusion protein by at most 5, 4, 3, 2 or 1 amino acid residues. In another embodiment, said two components are separated within the single-chain fusion protein by zero amino acid residues.

Thus, following cleavage at the second protease cleavage site, a polypeptide is provided with a targeting moiety that has an N-terminal domain and a C-terminal domain that are substantially free from the remainder of the conjugate. This arrangement facilitates interaction of the N-terminal and C-terminal components of the targeting moiety with a binding site on a target cell.

In one embodiment, the targeting moiety and the second protease cleavage site may be separated by a fourth spacer sequence, said fourth spacer sequence being located N-terminal or C-terminal of the targeting moiety. The fourth spacer sequence may be identical to (or different from) one, two or all of the first, second and third spacer sequences. In one embodiment, the fourth spacer sequence may comprise part or all of the second protease cleavage site, or may be part of the translocation domain component.

In one embodiment, the first protease (by which the first protease cleavage site is cleavable) is the same as the second protease (by which the second protease cleavage site is cleavable).

Thus, in one embodiment, treatment of the single-chain polypeptide fusion protein with a single protease may result in the cleavage of both the first and second protease cleavage sites.

A variety of different spacer molecules may be employed in any of the fusion proteins of the present invention. Examples of such spacer molecules include GS5, GS10, GS15, GS20, GS25, and Hx27.

The Covalent Linkage

The polypeptide fusion proteins of the present invention comprise two covalent linkages: the first such linkage is between the non-cytotoxic protease component and the remainder of the fusion protein; and the second such linkage is between the targeting moiety and the translocation domain. Following proteolytic cleavage at the (respective) first and second protease cleavage sites, said two covalent linkages remain intact. In one embodiment, the covalent linkages are not peptide bonds (i.e. the covalent linkages are non-peptide bonds). For example, in one embodiment, one or both of said covalent linkages are disulphide bonds.

Following proteolytic cleavage at the second protease cleavage site, the covalent linkage remains intact. Cleavage at the second protease cleavage site has the effect of exposing the N-terminus (or C-terminus) of the targeting moiety. Thus, cleavage at the second protease cleavage site produces a targeting moiety having a free N-terminus and a free C-terminus.

Thus, following cleavage at the second protease cleavage site the targeting moiety component is no longer part of the same polypeptide chain as the translocation domain component, as the peptide linkage between the targeting moiety and the translocation domain has been cleaved. However, the targeting moiety remains attached to the translocation domain due to the presence of the covalent linkage.

The covalent linkage may comprise any covalent linkage capable of forming or being formed between two amino acid residues in a polypeptide chain.

In one embodiment, the covalent linkage is a disulphide linkage. A disulphide linkage may be formed between any two thiol (i.e. —SH) groups present in the polypeptide. By way of example, disulphide linkages may form between two cysteine residues (or functionally equivalent variants thereof) located in a polypeptide chain.

Thus, in one embodiment, a cysteine residue located in the translocation domain component forms a covalent linkage with another cysteine residue located in the targeting moiety component. Such a disulphide linkage remains intact following cleavage at the second protease cleavage site.

The amino acid residues located in the translocation domain component and in the targeting moiety component that are joined by the covalent linkage may be present naturally in said components. Thus, in one embodiment the covalent linkage forms between an amino acid residue present naturally in the translocation domain component and an amino acid residue present naturally in the targeting moiety component. Alternatively, one or both of said amino acid residues may be introduced into the translocation domain component and/or the targeting moiety component. The amino acid residues may be introduced as substitutions.

In one embodiment, the covalent linkage is a disulphide linkage formed between a cysteine residue naturally present in the translocation domain component and a cysteine residue naturally present in the targeting moiety component. In an alternative embodiment, a cysteine residue is specifically introduced into either the translocation domain or the targeting moiety, or both, in order to facilitate or allow the formation of a disulphide linkage between these two components.

In one embodiment, one or more cysteine residue is introduced into the TM and/or translocation domain. When doing so, the introduced cysteine residue(s) may be flanked by two, small, achiral amino acid residues (such as glycine and/or alanine). Use of such amino acid residues avoids immediate tertiary structure and facilitates disulphide bond formation. The small, achiral amino acid residues may be present naturally, or may be introduced into the TM and/or translocation domain.

In one embodiment, in addition to the covalent linkage, there is located between the translocation domain and the targeting moiety a short polypeptide (e.g. 1-20, or 1-10, or 5-10 amino acid residues) that provides a secondary polypeptide structure. Said secondary polypeptide structure helps position the translocation domain and the targeting moiety, thereby assisting (1) formation of the covalent linkage between the TM and the translocation domain, and/or (2) positioning of the TM such that it's C-terminal and N-terminal ends face away from the translocation component.

Thus, in one embodiment the secondary polypeptide structure acts to bring part of the targeting moiety into close proximity to the translocation domain, thereby making formation of the covalent linkage energetically more favourable.

In one embodiment, a polypeptide capable of forming a secondary polypeptide structure as described above is a polypeptide sequence containing at least one ‘bulky’ amino acid residue such as a proline residue.

Thus, in one embodiment, there is located between the translocation domain and the targeting moiety a polypeptide comprising at least one bulky amino acid residue. Said bulky residue helps to form a bend in the polypeptide chain, such that part of the targeting moiety is brought into closer proximity with the translocation domain than would otherwise be the case.

The corresponding covalent linkage between the non-cytotoxic protease component and the remainder of the fusion protein (e.g. the translocation component and/or the TM component) may be formed in the same way as described above for the covalent linkage between the translocation domain component and the TM component. As described above, one or more secondary structure and/or one or more bulky amino acid residue may be introduced.

In one embodiment, the covalent linkage between the non-cytotoxic protease component and the remainder of the fusion protein is between the non-cytotoxic protease component and the translocation domain component. In one embodiment, the covalent linkage between the non-cytotoxic protease component and the translocation domain component employs naturally-occurring cysteine residues located on the respective components, such as for example one or more of the cysteine residues illustrated earlier in the description section. Alternatively, one or more appropriate cysteine residue(s) may be introduced into the respective components.

The fusion protein may comprise one or more purification tags, which are located N-terminal to the protease component and/or C-terminal to the translocation component.

Whilst any purification tag may be employed, the following are preferred:

His-tag (e.g. 6× histidine (SEQ ID NO: 47)), preferably as a C-terminal and/or N-terminal tag

MBP-tag (maltose binding protein), preferably as an N-terminal tag

GST-tag (glutathione-S-transferase), preferably as an N-terminal tag

His-MBP-tag, preferably as an N-terminal tag

GST-MBP-tag, preferably as an N-terminal tag

Thioredoxin-tag, preferably as an N-terminal tag

CBD-tag (Chitin Binding Domain), preferably as an N-terminal tag.

Therapeutic Applications

The TM component directs the targeted secretion inhibitor (TSI) therapeutic molecule of the present invention to the desired target cell.

By way of example, use of TMs described throughout this specification (such as an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, a BAM peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, an enkephalin peptide, a substance P peptide) direct the targeted secretion inhibitor (TSI) therapeutic molecule of the present invention to pain-sensing cells (e.g. primary sensory afferents). The resulting fusion proteins thus provide therapeutic molecules for suppressing pain—Applicant refers to WO2006/059093, WO2007/138339 and WO96/33273, each of which is incorporated in its entirety by reference thereto.

TMs described throughout this specification may be used to direct the targeted secretion inhibitor (TSI) molecules of the present invention to cells that promote neurogenic inflammation. Accordingly, the targeted secretion inhibitor (TSI) molecules of the present invention provide therapeutic molecules for suppressing neurogenic inflammation—Applicant refers to WO2010/138395, WO2010/138392, WO2010/138387, WO2010138382 and WO2010/138379, each of which is incorporated in its entirety by reference thereto. Preferred TMs for use in such TSI molecules and therapies include opioid TMs such as nociceptin and dynorphin.

TMs described throughout this specification may be used to direct the targeted secretion inhibitor (TSI) molecules of the present invention to cells that promote urogenital-neurological disorders such as over-active bladder. Accordingly, the targeted secretion inhibitor (TSI) molecules of the present invention provide therapeutic molecules for suppressing urogenital-neurological disorders such as over-active bladder—Applicant refers to WO2010/138393, WO2010/138389, WO2010/138384, and WO2010/138366, each of which is incorporated in its entirety by reference thereto. Preferred TMs for use in such TSI molecules and therapies include opioid TMs such as nociceptin and dynorphin.

TMs such as gonadotropin-releasing hormone (GnRH) peptide, CRF peptide, GRP peptide, Neuromedin B peptide, bombesin peptide, gastrin peptide, CCK peptide, SST peptide, CST peptide, and GHRH peptide may be used to direct the TSI molecules of the present invention to cells that promote cancer or indeed to cancerous cells per se. Accordingly, the targeted secretion inhibitor (TSI) molecules of the present invention provide therapeutic molecules for suppressing neuroendocrine conditions such as acromegaly and Cushing's disease and for suppressing cancer (e.g. lung cancer, renal cancer, brain cancer, breast cancer, pancreatic cancer, colorectal cancer, adrenal cancer, oesophageal cancer, lymphoma, leukaemia, acute leukaemia, bladder cancer, bone cancer, bowel cancer, cervical cancer, chronic lymphocytic leukaemia, Hodgkin's lymphoma, liver cancer, skin cancer, oropharyngeal cancer, myeloma, prostate cancer, gastric cancer, testicular cancer, uterine cancer or Kaposi sarcoma—Applicant refers to WO2009/150489, WO2009/150470 and WO2010/055358, each of which is incorporated in its entirety by reference thereto. Preferred TMs for use in such TSI molecules and therapies include GHRH peptides, SST peptides and CST peptides.

Destructive Cleavage Sites

The polypeptides of the present invention may be further modified to reduce or prevent unwanted side-effects associated with dispersal into non-targeted areas. According to this embodiment, the polypeptide comprises a destructive cleavage site. The destructive cleavage site is distinct from the ‘activation’ site (i.e. di-chain formation) and from the second protease cleavage site (i.e. formation of a TM with free C-terminal and N-terminal domains). Said destructive cleavage site is cleavable by a third protease and not by the first or second proteases. Moreover, when so cleaved at the destructive cleavage site by the third protease, the polypeptide of the invention has reduced potency (e.g. reduced binding ability to the intended target cell, reduced translocation activity and/or reduced non-cytotoxic protease activity). By way of example, Applicant refers to WO 2010/094905 & WO 02/044199, each of which is hereby incorporated in its entirety by reference thereto.

Thus, according to this embodiment, the present invention provides a polypeptide that can be controllably inactivated and/or destroyed at an off-site location.

In one embodiment, the destructive cleavage site is recognised and cleaved by a third protease (i.e. a destructive protease) selected from a circulating protease (e.g. an extracellular protease, such as a serum protease or a protease of the blood clotting cascade), a tissue-associated protease (e.g. a matrix metalloprotease (MMP), such as an MMP of muscle), and an intracellular protease (preferably a protease that is absent from the target cell). Thus, in use, should a polypeptide of the present invention become dispersed away from its intended target cell and/or be taken up by a non-target cell, the polypeptide will become inactivated by cleavage of the destructive cleavage site (by the third protease).

Matrix metalloproteases (MMPs) are a preferred group of destructive proteases in the context of the present invention. Within this group, ADAM17 (EC 3.4.24.86, also known as TACE), is preferred and cleaves a variety of membrane-anchored, cell-surface proteins to “shed” the extracellular domains. Additional, preferred MMPs include adamalysins, serralysins, and astacins. Another group of preferred destructive proteases is a mammalian blood protease, such as Thrombin, Coagulation Factor VIIa, Coagulation Factor IXa, Coagulation Factor Xa, Coagulation Factor XIa, Coagulation Factor XIIa, Kallikrein, Protein C, and MBP-associated serine protease.

In accordance with a second aspect of the present invention, there is provided a nucleic acid sequence encoding the above-described polypeptide fusion protein.

In a preferred aspect of the present invention, the DNA sequence is prepared as part of a DNA vector, wherein the vector comprises a promoter and terminator. The DNA sequence encoding the above-described polypeptide fusion protein is located downstream of the promoter; the terminator is located downstream of the nucleic acid sequence.

In a preferred embodiment, the vector has a promoter selected from:

Promoter Induction agent Typical induction condition tac (hybrid) IPTG 0.2 mM (0.05-2.0 mM) AraBAD L-arabinose 0.2% (0.002-0.4%) T7-lac operator IPTG 0.2 mM (0.05-2.0 mM)

The DNA construct of the present invention is preferably designed in silico, and then synthesised by conventional DNA synthesis techniques.

The above-mentioned DNA sequence information is optionally modified for codon-biasing according to the ultimate host cell (e.g. E. coli) expression system that is to be employed.

The DNA backbone is preferably screened for any inherent nucleic acid sequence, which when transcribed and translated would produce an amino acid sequence corresponding to the protease cleave site encoded by the second peptide-coding sequence. This screening may be performed manually or with the assistance of computer software (e.g. the MapDraw program by DNASTAR, Inc.).

According to another embodiment of the present invention, there is provided a method for preparing a single-chain polypeptide fusion protein as described above, comprising expressing a nucleic acid sequence encoding the above-described fusion protein, or a DNA vector as described above, in a host cell.

According to a further embodiment of the present invention, there is provided a method of preparing a non-cytotoxic agent, comprising:

-   -   a. providing a solution containing a single-chain polypeptide         fusion protein of the invention;     -   b. adding to said solution a first protease capable of cleaving         the first protease cleavage site and a second protease capable         of cleaving the second protease cleavage site;     -   c. cleaving the first protease cleavage site and the second         protease cleavage site;     -   thereby forming a tri-chain fusion protein.

In one embodiment, the first protease and the second protease are added sequentially. In an alternative embodiment, the second protease is added before the first protease. In yet another embodiment, the first protease and the second protease are added simultaneously.

This aspect provides a tri-chain polypeptide. In more detail, the resulting tri-chain polypeptide typically has a structure wherein:

-   -   a. the first chain comprises the non-cytotoxic protease, or a         fragment thereof, which protease or protease fragment is capable         of cleaving a protein of the exocytic fusion apparatus of a         target cell;     -   b. the second chain comprises the translocation domain that is         capable of translocating the protease or protease fragment from         within an endosome, across the endosomal membrane and into the         cytosol of the target cell;     -   c. the third chain comprises the targeting moiety that is         capable of binding to a binding site on the target cell, which         binding site is capable of undergoing endocytosis to be         incorporated into an endosome within the target cell;     -   d. the first and second chains are disulphide linked together;         and the second and third domains are linked together by a         non-peptide covalent linkage.

Polypeptide Delivery

According to a further aspect of the present invention, there is provided a single-chain polypeptide fusion protein as described above, or a non-cytotoxic polypeptide as described above, for use in treating, preventing or ameliorating a medical condition.

In use, the present invention employs a pharmaceutical composition, comprising a polypeptide, together with at least one component selected from a pharmaceutically acceptable carrier, excipient, adjuvant, propellant and/or salt.

The polypeptides of the present invention may be formulated for oral, parenteral, continuous infusion, implant, inhalation or topical application. Compositions suitable for injection may be in the form of solutions, suspensions or emulsions, or dry powders which are dissolved or suspended in a suitable vehicle prior to use.

Local delivery means may include an aerosol, or other spray (e.g. a nebuliser). In this regard, an aerosol formulation of a polypeptide enables delivery to the lungs and/or other nasal and/or bronchial or airway passages. A preferred route of administration is selected from: systemic (e.g. iv), laparoscopic and/or localised injection (for example, transsphenoidal injection directly into a target cell such as a tumour).

In the case of formulations for injection, it is optional to include a pharmaceutically active substance to assist retention at or reduce removal of the polypeptide from the site of administration. One example of such a pharmaceutically active substance is a vasoconstrictor such as adrenaline. Such a formulation confers the advantage of increasing the residence time of polypeptide following administration and thus increasing and/or enhancing its effect.

The dosage ranges for administration of the polypeptides of the present invention are those to produce the desired therapeutic effect. It will be appreciated that the dosage range required depends on the precise nature of the polypeptide or composition, the route of administration, the nature of the formulation, the age of the patient, the nature, extent or severity of the patient's condition, contraindications, if any, and the judgement of the attending physician. Variations in these dosage levels can be adjusted using standard empirical routines for optimisation.

Suitable daily dosages (per kg weight of patient) are in the range 0.0001-1 mg/kg, preferably 0.0001-0.5 mg/kg, more preferably 0.002-0.5 mg/kg, and particularly preferably 0.004-0.5 mg/kg. The unit dosage can vary from less that 1 microgram to 30 mg, but typically will be in the region of 0.01 to 1 mg per dose, which may be administered daily or preferably less frequently, such as weekly or six monthly. A particularly preferred dosing regimen is based on 2.5 ng of polypeptide as the 1× dose. In this regard, preferred dosages are in the range 1×-100× (i.e. 2.5-250 ng).

Fluid dosage forms are typically prepared utilising the polypeptide and a pyrogen-free sterile vehicle. The polypeptide, depending on the vehicle and concentration used, can be either dissolved or suspended in the vehicle. In preparing solutions the polypeptide can be dissolved in the vehicle, the solution being made isotonic if necessary by addition of sodium chloride and sterilised by filtration through a sterile filter using aseptic techniques before filling into suitable sterile vials or ampoules and sealing. Alternatively, if solution stability is adequate, the solution in its sealed containers may be sterilised by autoclaving. Advantageously additives such as buffering, solubilising, stabilising, preservative or bactericidal, suspending or emulsifying agents and or local anaesthetic agents may be dissolved in the vehicle.

Dry powders, which are dissolved or suspended in a suitable vehicle prior to use, may be prepared by filling pre-sterilised ingredients into a sterile container using aseptic technique in a sterile area. Alternatively the ingredients may be dissolved into suitable containers using aseptic technique in a sterile area. The product is then freeze dried and the containers are sealed aseptically.

Parenteral suspensions, suitable for intramuscular, subcutaneous or intradermal injection, are prepared in substantially the same manner, except that the sterile components are suspended in the sterile vehicle, instead of being dissolved and sterilisation cannot be accomplished by filtration. The components may be isolated in a sterile state or alternatively it may be sterilised after isolation, e.g. by gamma irradiation.

Advantageously, a suspending agent for example polyvinylpyrrolidone is included in the composition/s to facilitate uniform distribution of the components.

Definitions Section

Targeting Moiety (TM) means any chemical structure that functionally interacts with a Binding Site to cause a physical association between the polypeptide of the invention and the surface of a target cell. The term TM embraces any molecule (i.e. a naturally occurring molecule, or a chemically/physically modified variant thereof) that is capable of binding to a Binding Site on the target cell, which Binding Site is capable of internalisation (e.g. endosome formation)—also referred to as receptor-mediated endocytosis. The TM may possess an endosomal membrane translocation function, in which case separate TM and Translocation Domain components need not be present in an agent of the present invention. Throughout the preceding description, specific TMs have been described. Reference to said TMs is merely exemplary, and the present invention embraces all variants and derivatives thereof, which retain the basic binding (i.e. targeting) ability of the exemplified TMs.

As mentioned previously, preferred TMs include antibodies (e.g. antibody fragments) and binding scaffolds; especially commercially available antibodies/fragments and scaffolds designed for the purpose of binding (e.g. specifically) to target cells.

Protein scaffolds represent a new generation of universal binding frameworks to complement the expanding repertoire of therapeutic monoclonal antibodies and derivatives such as scFvs, Fab molecules, dAbs (single-domain antibodies), camelids, diabodies and minibodies, each of which may be employed as a TM of the present invention. Scaffold systems create or modify known protein recognition domains either through creation of novel scaffolds or modification of known protein binding domains. Such scaffolds include but are not limited to:

(i) protein A based scaffolds—affibodies (Nord, K. et al 1997 “Binding proteins selected from combinatorial libraries of an alpha-helical bacterial receptor domain”. Nat Biotechnol 15, 772-777);

(ii) lipocalin based scaffolds—anticalins (Skerra 2008 “Alternative binding proteins: anticalins—harnessing the structural plasticity of the lipocalin ligand pocket to engineer novel binding activities”. FEBS J. 275:2677-83);

(iii) fibronectin based scaffolds—adnectin (Dineen et al 2008 “The Adnectin CT-322 is a novel VEGF receptor 2 inhibitor that decreases tumor burden in an orthotopic mouse model of pancreatic cancer”. BMC Cancer 8:352);

(iv) avimers (Silverman et al 2005 “Multivalent avimer proteins evolved by exon shuffling of a family of human receptor domains”. Nat Biotechnol 23:1556-61);

(v) ankyrin based scaffolds—darpins (Zahnd et al 2006 “Selection and characterization of Her2 binding-designed ankyrin repeat proteins”. J Biol Chem. 281:35167-75); and

(vi) centyrin scaffolds—based on a protein fold that has significant structural homology to Ig domains with loops that are analogous to CDRs. Ig domains are a common module in human proteins and have been widely applied as alternative scaffold proteins. Each of the above ‘scaffold’ publications is hereby incorporated (in its entirety) by reference thereto.

Binding scaffolds can be used to target particular cell types via interaction with specific cell surface proteins, receptors or other cell surface epitopes such as sugar groups. Such modified scaffolds can be engineered onto recombinant non-cytotoxic protease based polypeptides of the present invention.

The TM of the present invention binds (preferably specifically binds) to the target cell in question. The term “specifically binds” preferably means that a given TM binds to the target cell with a binding affinity (Ka) of 10⁶ M⁻¹ or greater, preferably 10⁷ M⁻¹ or greater, more preferably 10⁸ M⁻¹ or greater, and most preferably, 10⁹ M⁻¹ or greater.

Reference to TM in the present specification embraces fragments and variants thereof, which retain the ability to bind to the target cell in question. By way of example, a variant may have at least 80%, preferably at least 90%, more preferably at least 95%, and most preferably at least 97 or at least 99% amino acid sequence homology with the reference TM. Thus, a variant may include one or more analogues of an amino acid (e.g. an unnatural amino acid), or a substituted linkage. Also, by way of example, the term fragment, when used in relation to a TM, means a peptide having at least ten, preferably at least twenty, more preferably at least thirty, and most preferably at least forty amino acid residues of the reference TM. The term fragment also relates to the above-mentioned variants. Thus, by way of example, a fragment of the present invention may comprise a peptide sequence having at least 10, 20, 30 or 40 amino acids, wherein the peptide sequence has at least 80% sequence homology over a corresponding peptide sequence (of contiguous) amino acids of the reference peptide.

It is routine to confirm that a TM binds to the selected target cell. For example, a simple radioactive displacement experiment may be employed in which tissue or cells representative of a target cell in question are exposed to labelled (e.g. tritiated) TM in the presence of an excess of unlabelled TM. In such an experiment, the relative proportions of non-specific and specific binding may be assessed, thereby allowing confirmation that the TM binds to the target cell. Optionally, the assay may include one or more binding antagonists, and the assay may further comprise observing a loss of TM binding. Examples of this type of experiment can be found in Hulme, E. C. (1990), Receptor-binding studies, a brief outline, pp. 303-311, In Receptor biochemistry, A Practical Approach, Ed. E. C. Hulme, Oxford University Press.

In the context of the present invention, reference to a peptide TM embraces peptide analogues thereof, so long as the analogue binds to the same receptor as the corresponding ‘reference’ TM. Said analogues may include synthetic residues such as:

β-Nal=β-naphthylalanine

β-Pal=β-pyridylalanine

hArg(Bu)=N-guanidino-(butyl)-homoarginine

hArg(Et)₂=N,N′-guanidino-(dimethyl)-homoarginine

hArg(CH₂CF₃)₂=N,N′-guanidino-bis-(2,2,2,-trifluoroethyl)-homoarginine

hArg(CH₃, hexyl)=N,N′-guanidino-(methyl, hexyl)-homoarginine

Lys(Me)=N^(e)-methyllysine

Lys(iPr)=N^(e)-isopropyllysine

AmPhe=aminomethylphenylalanine

AChxAla=aminocyclohexylalanine

Abu=α-aminobutyric acid

Tpo=4-thiaproline

MeLeu=N-methylleucine

Orn=ornithine

Nle—norleucine

Nva=norvaline

Trp(Br)=5-bromo-tryptophan

Trp(F)=5-fluoro-tryptophan

Trp(N0₂)=5-nitro-tryptophan

Gaba=γ-aminodutyric acid

Bmp=J-mercaptopropionyl

Ac=acetyl

Pen—pencillamine

The polypeptides of the present invention may lack a functional H_(C) or H_(CC) domain of a clostridial neurotoxin. Accordingly, said polypeptides are not able to bind rat synaptosomal membranes (via a clostridial H_(C) component) in binding assays as described in Shone et al. (1985) Eur. J. Biochem. 151, 75-82. In one embodiment, the polypeptides lack the last 50 C-terminal amino acids of a clostridial neurotoxin holotoxin. In another embodiment, the polypeptides lack the last 100, 150, 200, 250, or 300 C-terminal amino acid residues of a clostridial neurotoxin holotoxin. Alternatively, the H_(C) binding activity may be negated/reduced by mutagenesis—by way of example, referring to BoNT/A for convenience, modification of one or two amino acid residue mutations (W1266 to L and Y1267 to F) in the ganglioside binding pocket causes the H_(C) region to lose its receptor binding function. Analogous mutations may be made to non-serotype A clostridial peptide components, e.g. a construct based on botulinum B with mutations (W1262 to L and Y1263 to F) or botulinum E (W1224 to L and Y1225 to F). Other mutations to the active site achieve the same ablation of H_(C) receptor binding activity, e.g. Y1267S in botulinum type A toxin and the corresponding highly conserved residue in the other clostridial neurotoxins. Details of this and other mutations are described in Rummel et al (2004) (Molecular Microbiol. 51:631-634), which is hereby incorporated by reference thereto.

The H_(C) peptide of a native clostridial neurotoxin comprises approximately 400-440 amino acid residues, and consists of two functionally distinct domains of approximately 25 kDa each, namely the N-terminal region (commonly referred to as the H_(CN) peptide or domain) and the C-terminal region (commonly referred to as the H_(CC) peptide or domain). Moreover, it has been well documented that the C-terminal region (H_(CC)), which constitutes the C-terminal 160-200 amino acid residues, is responsible for binding of a clostridial neurotoxin to its natural cell receptors, namely to nerve terminals at the neuromuscular junction. Thus, reference throughout this specification to a clostridial heavy-chain lacking a functional heavy chain H_(C) peptide (or domain) such that the heavy-chain is incapable of binding to cell surface receptors to which a native clostridial neurotoxin binds means that the clostridial heavy-chain simply lacks a functional H_(CC) peptide. In other words, the H_(CC) peptide region is either partially or wholly deleted, or otherwise modified (e.g. through conventional chemical or proteolytic treatment) to inactivate its native binding ability for nerve terminals at the neuromuscular junction.

Thus, in one embodiment, a clostridial H_(N) peptide of the present invention lacks part of a C-terminal peptide portion (H_(CC)) of a clostridial neurotoxin and thus lacks the H_(C) binding function of native clostridial neurotoxin. By way of example, in one embodiment, the C-terminally extended clostridial H_(N) peptide lacks the C-terminal 40 amino acid residues, or the C-terminal 60 amino acid residues, or the C-terminal 80 amino acid residues, or the C-terminal 100 amino acid residues, or the C-terminal 120 amino acid residues, or the C-terminal 140 amino acid residues, or the C-terminal 150 amino acid residues, or the C-terminal 160 amino acid residues of a clostridial neurotoxin heavy-chain. In another embodiment, the clostridial H_(N) peptide of the present invention lacks the entire C-terminal peptide portion (H_(CC)) of a clostridial neurotoxin and thus lacks the H_(C) binding function of native clostridial neurotoxin. By way of example, in one embodiment, the clostridial H_(N) peptide lacks the C-terminal 165 amino acid residues, or the C-terminal 170 amino acid residues, or the C-terminal 175 amino acid residues, or the C-terminal 180 amino acid residues, or the C-terminal 185 amino acid residues, or the C-terminal 190 amino acid residues, or the C-terminal 195 amino acid residues of a clostridial neurotoxin heavy-chain. By way of further example, the clostridial H_(N) peptide of the present invention lacks a clostridial H_(CC) reference sequence selected from the group consisting of:

-   -   Botulinum type A neurotoxin—amino acid residues (Y1111-L1296)     -   Botulinum type B neurotoxin—amino acid residues (Y1098-E1291)     -   Botulinum type C neurotoxin—amino acid residues (Y1112-E1291)     -   Botulinum type D neurotoxin—amino acid residues (Y1099-E1276)     -   Botulinum type E neurotoxin—amino acid residues (Y1086-K1252)     -   Botulinum type F neurotoxin—amino acid residues (Y1106-E1274)     -   Botulinum type G neurotoxin—amino acid residues (Y1106-E1297)     -   Tetanus neurotoxin—amino acid residues (Y1128-D1315).

The above-identified reference sequences should be considered a guide as slight variations may occur according to sub-serotypes.

The protease of the present invention embraces all non-cytotoxic proteases that are capable of cleaving one or more proteins of the exocytic fusion apparatus in eukaryotic cells. The protease of the present invention is preferably a bacterial protease (or fragment thereof). More preferably the bacterial protease is selected from the genera Clostridium or Neisseria/Streptococcus (e.g. a clostridial L-chain, or a neisserial IgA protease preferably from N. gonorrhoeae or S. pneumoniae).

The present invention also embraces variant non-cytotoxic proteases (i.e. variants of naturally-occurring protease molecules), so long as the variant proteases still demonstrate the requisite protease activity. By way of example, a variant may have at least 70%, preferably at least 80%, more preferably at least 90%, and most preferably at least 95 or at least 98% amino acid sequence homology with a reference protease sequence. Thus, the term variant includes non-cytotoxic proteases having enhanced (or decreased) endopeptidase activity—particular mention here is made to the increased K_(cat)/K_(m) of BoNT/A mutants Q161A, E54A, and K165L see Ahmed, S. A. (2008) Protein J. DOI 10.1007/s10930-007-9118-8, which is incorporated by reference thereto. The term fragment, when used in relation to a protease, typically means a peptide having at least 150, preferably at least 200, more preferably at least 250, and most preferably at least 300 amino acid residues of the reference protease. As with the TM ‘fragment’ component (discussed above), protease ‘fragments’ of the present invention embrace fragments of variant proteases based on a reference sequence.

The protease of the present invention preferably demonstrates a serine or metalloprotease activity (e.g. endopeptidase activity). The protease is preferably specific for a SNARE protein (e.g. SNAP-25, synaptobrevin/VAMP, or syntaxin).

Particular mention is made to the protease domains of neurotoxins, for example the protease domains of bacterial neurotoxins. Thus, the present invention embraces the use of neurotoxin domains, which occur in nature, as well as recombinantly prepared versions of said naturally-occurring neurotoxins. Exemplary neurotoxins are produced by clostridia, and the term clostridial neurotoxin embraces neurotoxins produced by C. tetani (TeNT), and by C. botulinum (BoNT) serotypes A-G, as well as the closely related BoNT-like neurotoxins produced by C. baratii and C. butyricum. The above-mentioned abbreviations are used throughout the present specification. For example, the nomenclature BoNT/A denotes the source of neurotoxin as BoNT (serotype A).

BoNTs share a common structure, being di-chain proteins of ˜150 kDa, consisting of a heavy chain (H-chain) of ˜100 kDa covalently joined by a single disulphide bond to a light chain (L-chain) of ˜50 kDa. The H-chain consists of two domains, each of ˜50 kDa. The C-terminal domain (H_(C)) is required for the high-affinity neuronal binding, whereas the N-terminal domain (H_(N)) is proposed to be involved in membrane translocation. The L-chain is a zinc-dependent metalloprotease responsible for the cleavage of the substrate SNARE protein.

The term L-chain fragment means a component of the L-chain of a neurotoxin, which fragment demonstrates a metalloprotease activity and is capable of proteolytically cleaving a vesicle and/or plasma membrane associated protein involved in cellular exocytosis.

Examples of suitable protease (reference) sequences include:

-   -   Botulinum type A neurotoxin—amino acid residues (1-448)     -   Botulinum type B neurotoxin—amino acid residues (1-440)     -   Botulinum type C neurotoxin—amino acid residues (1-441)     -   Botulinum type D neurotoxin—amino acid residues (1-445)     -   Botulinum type E neurotoxin—amino acid residues (1-422)     -   Botulinum type F neurotoxin—amino acid residues (1-439)     -   Botulinum type G neurotoxin—amino acid residues (1-441)     -   Tetanus neurotoxin—amino acid residues (1-457)     -   IgA protease—amino acid residues (1-959)* * Pohlner, J. et al.         (1987). Nature 325, pp. 458-462, which is hereby incorporated by         reference thereto.

The above-identified reference sequence should be considered a guide as slight variations may occur according to sub-serotypes. By way of example, US 2007/0166332 (hereby incorporated by reference thereto) cites slightly different clostridial sequences:

-   -   Botulinum type A neurotoxin—amino acid residues (M1-K448)     -   Botulinum type B neurotoxin—amino acid residues (M1-K441)     -   Botulinum type C neurotoxin—amino acid residues (M1-K449)     -   Botulinum type D neurotoxin—amino acid residues (M1-R445)     -   Botulinum type E neurotoxin—amino acid residues (M1-R422)     -   Botulinum type F neurotoxin—amino acid residues (M1-K439)     -   Botulinum type G neurotoxin—amino acid residues (M1-K446)     -   Tetanus neurotoxin—amino acid residues (M1-A457)

A variety of clostridial toxin fragments comprising the light chain can be useful in aspects of the present invention with the proviso that these light chain fragments can specifically target the core components of the neurotransmitter release apparatus and thus participate in executing the overall cellular mechanism whereby a clostridial toxin proteolytically cleaves a substrate. The light chains of clostridial toxins are approximately 420-460 amino acids in length and comprise an enzymatic domain. Research has shown that the entire length of a clostridial toxin light chain is not necessary for the enzymatic activity of the enzymatic domain. As a non-limiting example, the first eight amino acids of the BoNT/A light chain are not required for enzymatic activity. As another non-limiting example, the first eight amino acids of the TeNT light chain are not required for enzymatic activity. Likewise, the carboxyl-terminus of the light chain is not necessary for activity. As a non-limiting example, the last 32 amino acids of the BoNT/A light chain (residues 417-448) are not required for enzymatic activity. As another non-limiting example, the last 31 amino acids of the TeNT light chain (residues 427-457) are not required for enzymatic activity. Thus, aspects of this embodiment can include clostridial toxin light chains comprising an enzymatic domain having a length of, for example, at least 350 amino acids, at least 375 amino acids, at least 400 amino acids, at least 425 amino acids and at least 450 amino acids. Other aspects of this embodiment can include clostridial toxin light chains comprising an enzymatic domain having a length of, for example, at most 350 amino acids, at most 375 amino acids, at most 400 amino acids, at most 425 amino acids and at most 450 amino acids.

In one embodiment, the non-cytotoxic protease cleaves a non-neuronal SNARE protein such as a SNAP-23 protein. In one embodiment, the non-cytotoxic protease is a modified botulinum toxin L-chain capable of cleaving SNAP-23. An example of such a modified L-chain is described by Chen and Barbieri, PNAS, vol. 106, no. 23, p 9180-9184, 2009.

In one embodiment, the non-cytotoxic protease is a BoNT/A, BoNT/C or BoNT/E protease, and the preferred SNARE motif is a SNAP (e.g. SNAP 25) motif. In another embodiment, the non-cytotoxic protease is a BoNT/B, BoNT/D, BoNT/F or BoNT/G or tetanus neurotoxin (TeNT) protease, and the preferred SNARE motif is a VAMP motif. In another embodiment, the non-cytotoxic protease is a BoNT/C, protease, and the preferred SNARE motif is a syntaxin motif.

The polypeptides of the present invention, especially the protease component thereof, may be PEGylated—this may help to increase stability, for example duration of action of the protease component. PEGylation is particularly preferred when the protease comprises a BoNT/A, B or C₁ protease. PEGylation preferably includes the addition of PEG to the N-terminus of the protease component. By way of example, the N-terminus of a protease may be extended with one or more amino acid (e.g. cysteine) residues, which may be the same or different. One or more of said amino acid residues may have its own PEG molecule attached (e.g. covalently attached) thereto. An example of this technology is described in WO2007/104567, which is incorporated in its entirety by reference thereto.

A Translocation Domain is a molecule that enables translocation of a protease into a target cell such that a functional expression of protease activity occurs within the cytosol of the target cell. Whether any molecule (e.g. a protein or peptide) possesses the requisite translocation function of the present invention may be confirmed by any one of a number of conventional assays.

For example, Shone C. (1987) describes an in vitro assay employing liposomes, which are challenged with a test molecule. Presence of the requisite translocation function is confirmed by release from the liposomes of K⁺ and/or labelled NAD, which may be readily monitored [see Shone C. (1987) Eur. J. Biochem; vol. 167(1): pp. 175-180]. A further example is provided by Blaustein R. (1987), which describes a simple in vitro assay employing planar phospholipid bilayer membranes. The membranes are challenged with a test molecule and the requisite translocation function is confirmed by an increase in conductance across said membranes [see Blaustein (1987) FEBS Letts; vol. 226, no. 1: pp. 115-120]. Additional methodology to enable assessment of membrane fusion and thus identification of Translocation Domains suitable for use in the present invention are provided by Methods in Enzymology Vol 220 and 221, Membrane Fusion Techniques, Parts A and B, Academic Press 1993.

The present invention also embraces variant translocation domains, so long as the variant domains still demonstrate the requisite translocation activity. By way of example, a variant may have at least 70%, preferably at least 80%, more preferably at least 90%, and most preferably at least 95% or at least 98% amino acid sequence homology with a reference translocation domain. The term fragment, when used in relation to a translocation domain, means a peptide having at least 20, preferably at least 40, more preferably at least 80, and most preferably at least 100 amino acid residues of the reference translocation domain. In the case of a clostridial translocation domain, the fragment preferably has at least 100, preferably at least 150, more preferably at least 200, and most preferably at least 250 amino acid residues of the reference translocation domain (e.g. H_(N) domain). As with the TM ‘fragment’ component (discussed above), translocation ‘fragments’ of the present invention embrace fragments of variant translocation domains based on the reference sequences.

It is well documented that certain domains of bacterial toxin molecules are capable of forming such pores. It is also known that certain translocation domains of virally expressed membrane fusion proteins are capable of forming such pores. Such domains may be employed in the present invention.

The Translocation Domain may be of a clostridial origin, such as the H_(N) domain (or a functional component thereof). H_(N) means a portion or fragment of the H-chain of a clostridial neurotoxin approximately equivalent to the amino-terminal half of the H-chain, or the domain corresponding to that fragment in the intact H-chain. In this regard, should it be desired to remove the H_(C) cell-binding function, this may be done by deletion of the H_(C) or H_(CC) amino acid sequence (either at the DNA synthesis level, or at the post-synthesis level by nuclease or protease treatment). Alternatively, the H_(C) function may be inactivated by chemical or biological treatment.

Examples of suitable (reference) Translocation Domains include:

-   -   Botulinum type A neurotoxin—amino acid residues (449-871)     -   Botulinum type B neurotoxin—amino acid residues (441-858)     -   Botulinum type C neurotoxin—amino acid residues (442-866)     -   Botulinum type D neurotoxin—amino acid residues (446-862)     -   Botulinum type E neurotoxin—amino acid residues (423-845)     -   Botulinum type F neurotoxin—amino acid residues (440-864)     -   Botulinum type G neurotoxin—amino acid residues (442-863)     -   Tetanus neurotoxin—amino acid residues (458-879)

The above-identified reference sequence should be considered a guide as slight variations may occur according to sub-serotypes. By way of example, US 2007/0166332 (hereby incorporated by reference thereto) cites slightly different clostridial sequences:

-   -   Botulinum type A neurotoxin—amino acid residues (A449-K871)     -   Botulinum type B neurotoxin—amino acid residues (A442-5858)     -   Botulinum type C neurotoxin—amino acid residues (T450-N866)     -   Botulinum type D neurotoxin—amino acid residues (D446-N862)     -   Botulinum type E neurotoxin—amino acid residues (K423-K845)     -   Botulinum type F neurotoxin—amino acid residues (A440-K864)     -   Botulinum type G neurotoxin—amino acid residues (S447-S863)     -   Tetanus neurotoxin—amino acid residues (S458-V879)

In the context of the present invention, a variety of clostridial toxin H_(N) regions comprising a translocation domain can be useful in aspects of the present invention with the proviso that these active fragments can facilitate the release of a non-cytotoxic protease (e.g. a clostridial L-chain) from intracellular vesicles into the cytoplasm of the target cell and thus participate in executing the overall cellular mechanism whereby a clostridial toxin proteolytically cleaves a substrate. The H_(N) regions from the heavy chains of Clostridial toxins are approximately 410-430 amino acids in length and comprise a translocation domain. Research has shown that the entire length of a H_(N) region from a Clostridial toxin heavy chain is not necessary for the translocating activity of the translocation domain. Thus, aspects of this embodiment can include clostridial toxin H_(N) regions comprising a translocation domain having a length of, for example, at least 350 amino acids, at least 375 amino acids, at least 400 amino acids and at least 425 amino acids. Other aspects of this embodiment can include clostridial toxin H_(N) regions comprising translocation domain having a length of, for example, at most 350 amino acids, at most 375 amino acids, at most 400 amino acids and at most 425 amino acids.

For further details on the genetic basis of toxin production in Clostridium botulinum and C. tetani, we refer to Henderson et al (1997) in The Clostridia: Molecular Biology and Pathogenesis, Academic press. The term H_(N) embraces naturally-occurring neurotoxin H_(N) portions, and modified H_(N) portions having amino acid sequences that do not occur in nature and/or synthetic amino acid residues, so long as the modified H_(N) portions still demonstrate the above-mentioned translocation function.

Alternatively, the Translocation Domain may be of a non-clostridial origin. Examples of non-clostridial (reference) Translocation Domain origins include, but not be restricted to, the translocation domain of diphtheria toxin [O'Keefe et al., Proc. Natl. Acad. Sci. USA (1992) 89, 6202-6206; Silverman et al., J. Biol. Chem. (1993) 269, 22524-22532; and London, E. (1992) Biochem. Biophys. Acta., 1112, pp. 25-51], the translocation domain of Pseudomonas exotoxin type A [Prior et al. Biochemistry (1992) 31, 3555-3559], the translocation domains of anthrax toxin [Blanke et al. Proc. Natl. Acad. Sci. USA (1996) 93, 8437-8442], a variety of fusogenic or hydrophobic peptides of translocating function [Plank et al. J. Biol. Chem. (1994) 269, 12918-12924; and Wagner et al (1992) PNAS, 89, pp. 7934-7938], and amphiphilic peptides [Murata et al (1992) Biochem., 31, pp. 1986-1992]. The Translocation Domain may mirror the Translocation Domain present in a naturally-occurring protein, or may include amino acid variations so long as the variations do not destroy the translocating ability of the Translocation Domain.

Particular examples of viral (reference) Translocation Domains suitable for use in the present invention include certain translocating domains of virally expressed membrane fusion proteins. For example, Wagner et al. (1992) and Murata et al. (1992) describe the translocation (i.e. membrane fusion and vesiculation) function of a number of fusogenic and amphiphilic peptides derived from the N-terminal region of influenza virus haemagglutinin. Other virally expressed membrane fusion proteins known to have the desired translocating activity are a translocating domain of a fusogenic peptide of Semliki Forest Virus (SFV), a translocating domain of vesicular stomatitis virus (VSV) glycoprotein G, a translocating domain of SER virus F protein and a translocating domain of Foamy virus envelope glycoprotein. Virally encoded Aspike proteins have particular application in the context of the present invention, for example, the E1 protein of SFV and the G protein of the G protein of VSV.

Use of the (reference) Translocation Domains includes use of sequence variants thereof. A variant may comprise one or more conservative nucleic acid substitutions and/or nucleic acid deletions or insertions, with the proviso that the variant possesses the requisite translocating function. A variant may also comprise one or more amino acid substitutions and/or amino acid deletions or insertions, so long as the variant possesses the requisite translocating function.

The polypeptides of the present invention may further comprise a translocation facilitating domain. Said domain facilitates delivery of the non-cytotoxic protease into the cytosol of the target cell and are described, for example, in WO 08/008803 and WO 08/008805, each of which is herein incorporated by reference thereto.

By way of example, suitable translocation facilitating domains include an enveloped virus fusogenic peptide domain, for example, suitable fusogenic peptide domains include influenzavirus fusogenic peptide domain (e.g. influenza A virus fusogenic peptide domain of 23 amino acids), alphavirus fusogenic peptide domain (e.g. Semliki Forest virus fusogenic peptide domain of 26 amino acids), vesiculovirus fusogenic peptide domain (e.g. vesicular stomatitis virus fusogenic peptide domain of 21 amino acids), respirovirus fusogenic peptide domain (e.g. Sendai virus fusogenic peptide domain of 25 amino acids), morbiliivirus fusogenic peptide domain (e.g. Canine distemper virus fusogenic peptide domain of 25 amino acids), avulavirus fusogenic peptide domain (e.g. Newcastle disease virus fusogenic peptide domain of 25 amino acids), henipavirus fusogenic peptide domain (e.g. Hendra virus fusogenic peptide domain of 25 amino acids), metapneumovirus fusogenic peptide domain (e.g. Human metapneumovirus fusogenic peptide domain of 25 amino acids) or spumavirus fusogenic peptide domain such as simian foamy virus fusogenic peptide domain; or fragments or variants thereof.

By way of further example, a translocation facilitating domain may comprise a Clostridial toxin H_(CN) domain or a fragment or variant thereof. In more detail, a Clostridial toxin H_(CN) translocation facilitating domain may have a length of at least 200 amino acids, at least 225 amino acids, at least 250 amino acids, at least 275 amino acids. In this regard, a Clostridial toxin H_(CN) translocation facilitating domain preferably has a length of at most 200 amino acids, at most 225 amino acids, at most 250 amino acids, or at most 275 amino acids. Specific (reference) examples include:

-   -   Botulinum type A neurotoxin—amino acid residues (872-1110)     -   Botulinum type B neurotoxin—amino acid residues (859-1097)     -   Botulinum type C neurotoxin—amino acid residues (867-1111)     -   Botulinum type D neurotoxin—amino acid residues (863-1098)     -   Botulinum type E neurotoxin—amino acid residues (846-1085)     -   Botulinum type F neurotoxin—amino acid residues (865-1105)     -   Botulinum type G neurotoxin—amino acid residues (864-1105)     -   Tetanus neurotoxin—amino acid residues (880-1127)

The above sequence positions may vary a little according to serotype/sub-type, and further examples of suitable (reference) Clostridial toxin H_(CN) domains include:

-   -   Botulinum type A neurotoxin—amino acid residues (874-1110)     -   Botulinum type B neurotoxin—amino acid residues (861-1097)     -   Botulinum type C neurotoxin—amino acid residues (869-1111)     -   Botulinum type D neurotoxin—amino acid residues (865-1098)     -   Botulinum type E neurotoxin—amino acid residues (848-1085)     -   Botulinum type F neurotoxin—amino acid residues (867-1105)     -   Botulinum type G neurotoxin—amino acid residues (866-1105)     -   Tetanus neurotoxin—amino acid residues (882-1127)

Any of the above-described facilitating domains may be combined with any of the previously described translocation domain peptides that are suitable for use in the present invention. Thus, by way of example, a non-clostridial facilitating domain may be combined with non-clostridial translocation domain peptide or with clostridial translocation domain peptide. Alternatively, a Clostridial toxin H_(CN) translocation facilitating domain may be combined with a non-clostridal translocation domain peptide. Alternatively, a Clostridial toxin H_(CN) facilitating domain may be combined or with a clostridial translocation domain peptide, examples of which include:

-   -   Botulinum type A neurotoxin—amino acid residues (449-1110)     -   Botulinum type B neurotoxin—amino acid residues (442-1097)     -   Botulinum type C neurotoxin—amino acid residues (450-1111)     -   Botulinum type D neurotoxin—amino acid residues (446-1098)     -   Botulinum type E neurotoxin—amino acid residues (423-1085)     -   Botulinum type F neurotoxin—amino acid residues (440-1105)     -   Botulinum type G neurotoxin—amino acid residues (447-1105)     -   Tetanus neurotoxin—amino acid residues (458-1127)

Sequence Homology

Any of a variety of sequence alignment methods can be used to determine percent identity, including, without limitation, global methods, local methods and hybrid methods, such as, e.g., segment approach methods. Protocols to determine percent identity are routine procedures within the scope of one skilled in the. Global methods align sequences from the beginning to the end of the molecule and determine the best alignment by adding up scores of individual residue pairs and by imposing gap penalties. Non-limiting methods include, e.g., CLUSTAL W, see, e.g., Julie D. Thompson et al., CLUSTAL W: Improving the Sensitivity of Progressive Multiple Sequence Alignment Through Sequence Weighting, Position-Specific Gap Penalties and Weight Matrix Choice, 22(22) Nucleic Acids Research 4673-4680 (1994); and iterative refinement, see, e.g., Osamu Gotoh, Significant Improvement in Accuracy of Multiple Protein. Sequence Alignments by Iterative Refinement as Assessed by Reference to Structural Alignments, 264(4) J. Mol. Biol. 823-838 (1996). Local methods align sequences by identifying one or more conserved motifs shared by all of the input sequences. Non-limiting methods include, e.g., Match-box, see, e.g., Eric Depiereux and Ernest Feytmans, Match-Box: A Fundamentally New Algorithm for the Simultaneous Alignment of Several Protein Sequences, 8(5) CABIOS 501-509 (1992); Gibbs Sampling, see, e.g., C. E. Lawrence et al., Detecting Subtle Sequence Signals: A Gibbs Sampling Strategy for Multiple Alignment, 262(5131) Science 208-214 (1993): Align-M, see, e.g., Ivo Van Walle et al., Align-M—A New Algorithm for Multiple Alignment of Highly Divergent Sequences, 20(9) Bioinformatics:1428-1435 (2004). Thus, percent sequence identity is determined by conventional methods. See, for example, Altschul et al., Bull. Math. Bio. 48: 603-16, 1986 and Henikoff and Henikoff, Proc. Natl. Acad. Sci. USA 89:10915-19, 1992. Briefly, two amino acid sequences are aligned to optimize the alignment scores using a gap opening penalty of 10, a gap extension penalty of 1, and the “blosum 62” scoring matrix of Henikoff and Henikoff.

Substantially homologous polypeptides are characterized as having one or more amino acid substitutions, deletions or additions. These changes are preferably of a minor nature, that is conservative amino acid substitutions (see below) and other substitutions that do not significantly affect the folding or activity of the polypeptide; small deletions, typically of one to about 30 amino acids; and small amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue, a small linker peptide of up to about 20-25 residues, or an affinity tag.

Conservative Amino Acid Substitutions

Basic: arginine; lysine; histidine

Acidic: glutamic acid; aspartic acid;

Polar: glutamine; asparagine

Hydrophobic: leucine; isoleucine; valine

Aromatic: phenylalanine; tryptophan; tyrosine

Small: glycine; alanine; serine; threonine; methionine

In addition to the 20 standard amino acids, non-standard amino acids (such as 4-hydroxyproline, 6-N-methyl lysine, 2-aminoisobutyric acid, isovaline and α-methyl serine) may be substituted for amino acid residues of the polypeptides of the present invention. A limited number of non-conservative amino acids, amino acids that are not encoded by the genetic code, and unnatural amino acids may be substituted for clostridial polypeptide amino acid residues. The polypeptides of the present invention can also comprise non-naturally occurring amino acid residues.

Non-naturally occurring amino acids include, without limitation, trans-3-methylproline, 2,4-methano-proline, cis-4-hydroxyproline, trans-4-hydroxy-proline, N-methylglycine, allo-threonine, methyl-threonine, hydroxy-ethylcysteine, hydroxyethylhomo-cysteine, nitro-glutamine, homoglutamine, pipecolic acid, tert-leucine, norvaline, 2-azaphenylalanine, 3-azaphenyl-alanine, 4-azaphenyl-alanine, and 4-fluorophenylalanine. Several methods are known in the art for incorporating non-naturally occurring amino acid residues into proteins. For example, an in vitro system can be employed wherein nonsense mutations are suppressed using chemically aminoacylated suppressor tRNAs. Methods for synthesizing amino acids and aminoacylating tRNA are known in the art. Transcription and translation of plasmids containing nonsense mutations is carried out in a cell free system comprising an E. coli S30 extract and commercially available enzymes and other reagents. Proteins are purified by chromatography. See, for example, Robertson et al., J. Am. Chem. Soc. 113:2722, 1991; Ellman et al., Methods Enzymol. 202:301, 1991; Chung et al., Science 259:806-9, 1993; and Chung et al., Proc. Natl. Acad. Sci. USA 90:10145-9, 1993). In a second method, translation is carried out in Xenopus oocytes by microinjection of mutated mRNA and chemically aminoacylated suppressor tRNAs (Turcatti et al., J. Biol. Chem. 271:19991-8, 1996). Within a third method, E. coli cells are cultured in the absence of a natural amino acid that is to be replaced (e.g., phenylalanine) and in the presence of the desired non-naturally occurring amino acid(s) (e.g., 2-azaphenylalanine, 3-azaphenylalanine, 4-azaphenylalanine, or 4-fluorophenylalanine). The non-naturally occurring amino acid is incorporated into the polypeptide in place of its natural counterpart. See, Koide et al., Biochem. 33:7470-6, 1994. Naturally occurring amino acid residues can be converted to non-naturally occurring species by in vitro chemical modification. Chemical modification can be combined with site-directed mutagenesis to further expand the range of substitutions (Wynn and Richards, Protein Sci. 2:395-403, 1993).

A limited number of non-conservative amino acids, amino acids that are not encoded by the genetic code, non-naturally occurring amino acids, and unnatural amino acids may be substituted for amino acid residues of polypeptides of the present invention.

Essential amino acids in the polypeptides of the present invention can be identified according to procedures known in the art, such as site-directed mutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, Science 244: 1081-5, 1989). Sites of biological interaction can also be determined by physical analysis of structure, as determined by such techniques as nuclear magnetic resonance, crystallography, electron diffraction or photoaffinity labeling, in conjunction with mutation of putative contact site amino acids. See, for example, de Vos et al., Science 255:306-12, 1992; Smith et al., J. Mol. Biol. 224:899-904, 1992; Wlodaver et al., FEBS Lett. 309:59-64, 1992. The identities of essential amino acids can also be inferred from analysis of homologies with related components (e.g. the translocation or protease components) of the polypeptides of the present invention.

Multiple amino acid substitutions can be made and tested using known methods of mutagenesis and screening, such as those disclosed by Reidhaar-Olson and Sauer (Science 241:53-7, 1988) or Bowie and Sauer (Proc. Natl. Acad. Sci. USA 86:2152-6, 1989). Briefly, these authors disclose methods for simultaneously randomizing two or more positions in a polypeptide, selecting for functional polypeptide, and then sequencing the mutagenised polypeptides to determine the spectrum of allowable substitutions at each position. Other methods that can be used include phage display (e.g., Lowman et al., Biochem. 30:10832-7, 1991; Ladner et al., U.S. Pat. No. 5,223,409; Huse, WIPO Publication WO 92/06204) and region-directed mutagenesis (Derbyshire et al., Gene 46:145, 1986; Ner et al., DNA 7:127, 1988).

Multiple amino acid substitutions can be made and tested using known methods of mutagenesis and screening, such as those disclosed by Reidhaar-Olson and Sauer (Science 241:53-7, 1988) or Bowie and Sauer (Proc. Natl. Acad. Sci. USA 86:2152-6, 1989). Briefly, these authors disclose methods for simultaneously randomizing two or more positions in a polypeptide, selecting for functional polypeptide, and then sequencing the mutagenized polypeptides to determine the spectrum of allowable substitutions at each position. Other methods that can be used include phage display (e.g., Lowman et al., Biochem. 30:10832-7, 1991; Ladner et al., U.S. Pat. No. 5,223,409; Huse, WIPO Publication WO 92/06204) and region-directed mutagenesis (Derbyshire et al., Gene 46:145, 1986; Ner et al., DNA 7:127, 1988).

SUMMARY OF EXAMPLES

Example 1 Creation of an LHD protein that incorporates a GnRH polypeptide to the C-terminus of the H_(N) domain

Example 2 Creation of an LHA protein that incorporates a GnRH polypeptide to the C-terminus of the H_(N) domain

Example 3 Creation of an LHD protein that incorporates a GnRH polypeptide to the C-terminus of the H_(N) domain, where two different protease recognition sites are incorporated

Example 4 Method of preparation of an LHD protein that incorporates a GnRH polypeptide to the C-terminus of the H_(N) domain

Example 5 Demonstration of presence of covalently attached ligand by Western blotting

Example 6 Demonstration of presence of covalently attached TM by mass spectrometry

Example 7 Assessment of the binding ability of an LHD protein that incorporates a GnRH polypeptide

Example 8 Assessment of the in vitro functionality of an LHD protein that incorporates a GnRH polypeptide

Example 9 Creation of an LHD protein that incorporates a dynorphin and a bradykinin polypeptide to the C-terminus of the H_(N) domain

Example 10 Creation of an LHA protein that incorporates a beta-endorphin and a bradykinin polypeptide to the C-terminus of the H_(N) domain

Example 11 Creation of an LHD protein that incorporates two GHRH polypeptides to the C-terminus of the H_(N) domain

Example 12 Creation of an LHD protein that incorporates a GnRH polypeptide to the C-terminus of the H_(N) domain, spaced by 5 amino acids from the second protease activation site

Example 13 Creation of an LHA protein that incorporates a Gastrin releasing peptide to the C-terminus of the H_(N) domain

Example 14 Method of treating patients suffering from prostate cancer

Example 15 Method of treating patients suffering from neurogenic inflammation

Example 16 Method of treating patients suffering from endometriosis

SUMMARY OF SEQ ID NOS

All of the following SEQ ID NOs may exclude any initial Methionine amino acid residue (or corresponding N-terminal nucleic acid codon/sequence).

-   SEQ ID NO: 1 DNA sequence of LHD-GnRH -   SEQ ID NO: 2 Protein sequence of LHD-GnRH -   SEQ ID NO: 3 DNA sequence of LHA-GnRH -   SEQ ID NO: 4 Protein sequence of LHA-GnRH -   SEQ ID NO: 5 DNA sequence of LHD-GnRH with two different protease     sites -   SEQ ID NO: 6 Protein sequence of LHD-GnRH with two different     protease sites -   SEQ ID NO: 7 DNA sequence of LHD that incorporates a dynorphin and a     bradykinin polypeptide to the C-terminus of the H_(N) domain -   SEQ ID NO: 8 Protein sequence of LHD that incorporates a dynorphin     and a bradykinin polypeptide to the C-terminus of the H_(N) domain -   SEQ ID NO: 9 DNA sequence of LHA that incorporates a beta-endorphin     and a bradykinin polypeptide to the C-terminus of the H_(N) domain -   SEQ ID NO: 10 Protein sequence of LHA that incorporates a     beta-endorphin and a bradykinin polypeptide to the C-terminus of the     H_(N) domain -   SEQ ID NO: 11 DNA sequence of LHD that incorporates two GHRH     polypeptides to the C-terminus of the H_(N) domain -   SEQ ID NO: 12 Protein sequence of LHD that incorporates two GHRH     polypeptides to the C-terminus of the H_(N) domain -   SEQ ID NO: 13 DNA sequence of LHD that incorporates GnRH to the     C-terminus of the H_(N) domain -   SEQ ID NO: 14 Protein sequence of LHD that incorporates GnRH to the     C-terminus of the H_(N) domain -   SEQ ID NO: 15 DNA sequence of LHA that incorporates a Gastrin     releasing peptide to the C-terminus of the H_(N) domain -   SEQ ID NO: 16 Protein sequence of LHA that incorporates a Gastrin     releasing peptide to the C-terminus of the H_(N) domain

There now follows description of specific embodiments of the invention, illustrated by the Examples.

Example 1 Creation of an LHD Protein that Incorporates a GnRH Polypeptide to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/D and the 10 amino acid peptide GnRH is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the TM (GnRH).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/D,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/D modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 10 amino acid GnRH peptide modified to incorporate a Cys         residue at position 6 in place of the natural Gly (QHWSYCLRPG)         (SEQ ID NO: 51).

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 1 and the amino acid sequence of the expression product is illustrated in SEQ ID 2.

Example 2 Creation of an LHA Protein that Incorporates a GnRH Polypeptide to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/A and the 10 amino acid peptide GnRH is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the TM (GnRH).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/A,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/A modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 10 amino acid GnRH peptide modified to incorporate a Cys         residue at position 6 in place of the natural Gly.

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 3 and the amino acid sequence of the expression product is illustrated in SEQ ID 4.

Example 3 Creation of an LHD Protein that Incorporates a GnRH Polypeptide to the C-Terminus of the H_(N) Domain, where Two Different Protease Recognition Sites are Incorporated

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/D and the 10 amino acid peptide GnRH is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33) and enterokinase (DDDDK) (SEQ ID NO: 32). As no such string is found, the choice is made to use FXa as the protease to activate the fusion protein at the LC-H_(N) junction and enterokinase to cleave the peptide bond between the H_(N) and the TM (GnRH).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 amino acid asparagine spacer (SEQ ID NO: 49),     -   the LC of BoNT/D,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/D modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating a         DDDDK (SEQ ID NO: 32) peptide sequence at the C-terminus     -   a 10 amino acid GnRH peptide modified to incorporate a Cys         residue at position 6 in place of the natural Gly.

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 5 and the amino acid sequence of the expression product is illustrated in SEQ ID 6.

Example 4 Method of Preparation of an LHD Protein that Incorporates a GnRH Polypeptide to the C-Terminus of the H_(N) Domain

The ORF created in Example 1 was cloned into an E. coli expression vector (a pET (Novagen) vector that has been modified to ensure mobilisation deficiency) and transformed into an E. coli host strain, most commonly BL21.

Expression of the LHD-GnRH fusion protein is achieved using the following protocol. Inoculate 100 ml of modified TB containing 0.2% glucose and 100 μg/ml ampicillin in a 250 ml flask with a single colony from the LHD-GnRH expression strain. Grow the culture at 37° C., 225 rpm for 16 hours. Inoculate 2×1 L of modified TB containing 0.2% glucose and 100 μg/ml ampicillin in a 2×2 L flask with 10 ml of overnight culture. Grow cultures at 37° C. until an approximate OD600 nm of 0.5 is reached at which point reduce the temperature to 16° C. After 1 hour induce the cultures with 1 mM IPTG and grow at 16° C. for a further 16 hours. Centrifugation of the culture yielded 35.2 g cell paste.

Purification of the LHD-GnRH fusion is achieved by affinity chromatography. In detail, a falcon tube containing 25 ml 50 mM HEPES pH 7.2 200 mM NaCl and approximately 10 g of E. coli BL21 cell paste is defrosted. Sonicate the cell paste on ice 30 seconds on, 30 seconds off for 10 cycles at a power of 22 microns ensuring the sample remains cool. Spin the lysed cells at 18 000 rpm, 4° C. for 30 minutes. Load the supernatant onto a HisTrap HP Chelating column (5 ml column is sufficient) equilibrated with 50 mM HEPES pH 7.2 200 mM NaCl. Following addition of 40 mM Imidazole to wash away the non-specific bound protein, fusion protein was eluted with a step gradient of 80 mM Imidazole, 250 mM Imidazole and 500 mM Imidazole. Dialyse the eluted fusion protein against 5 L of 50 mM HEPES pH 7.2 200 mM NaCl at 4° C. overnight and measure the OD of the dialysed fusion protein. Add 10 U Factor Xa/mg fusion protein and incubate at 25° C. static overnight. Load onto a HisTrap HP Chelating column (5 ml column is sufficient) equilibrated with 50 mM HEPES pH 7.2 200 mM NaCl. Wash column to baseline with 50 mM HEPES pH 7.2 200 mM NaCl. Using a step gradient of 10 and 40 mM imidazole, wash away the non-specific bound protein and elute the fusion protein with 100 mM imidazole. Dialyse the eluted fusion protein against 5 L of 25 mM Tris, 200 mM NaCl, pH 8.0 at 4° C. overnight and concentrate the fusion to about 2 mg/ml, aliquot sample and freeze at −20° C. Test purified protein using OD, BCA and purity analysis.

Samples of the activated protein are analysed by SDS-PAGE in both reducing and non-reducing conditions. Samples eluted in the 80 mM and 250 mM Imidazole fractions are analysed—see FIG. 1.

Example 5 Demonstration of Presence of Covalently Attached TM by Western Blotting

The presence of the TM within the fusion protein may be assessed by a variety of methods. One method is to use specific antisera to the TM and visualise by SDS-PAGE and Western blotting. Antibodies to TM may be obtained commercially (e.g. anti-GnRH antibodies are available from Abcam (AB76560) or Novus Biologicals (H00002796-B01) or may be raised specifically to a given peptide sequence by a commercial service provider.

Using such techniques, the presence of GnRH is confirmed to be within the full length, activated fusion protein when run under non-reducing conditions, but it not present on the H_(N) domain when run under reducing conditions.

Example 6 Demonstration of the Presence of Covalently Attached TM by Mass Spectrometry

The presence of the TM within the fusion protein may be assessed by a variety of methods. One method is the use of mass spectrometry to determine the fusion protein mass before and after reduction.

Using the protein prepared according to Example 4, various samples of non-reduced and reduced protein were extracted from SDS-PAGE (see FIG. 1) and analysed by mass spectrometry (Intertek, Manchester).

The predicted mass of non-activated, non-reduced fusion protein is 105271 Da. The observed mass for the samples was 105284 Da, a difference of only 13 Da, which is within the error of the equipment. Therefore, the presence of the intact GnRH in the non-activated, non-reduced fusion protein is confirmed.

Non-Reduced Sample: Theoretical Corresponding Observed Mass Mass: Structure: Mass: Difference: 105271 Da Full Length 105284 Da 13 Da

The predicted mass of activated, non-reduced fusion protein is 105271 Da. The observed mass for the samples was 105321 Da, a difference of only 50 Da, which is within the error of the equipment. Therefore, the presence of the intact GnRH in the activated, non-reduced fusion protein is confirmed.

Non-Reduced Sample: Theoretical Corresponding Observed Mass Mass: Structure: Mass: Difference: 105271 Da Full Length 105321 Da 50 Da

When reduced samples of the LC and H_(N) domain are assessed, the H_(N) domain (which should comprise H_(N)+spacer+activation site) has a predicted mass of 49419 Da and an observed mass of 49421. This indicates that the reduced H_(N) domain does not retain the GnRH peptide. This result is entirely as predicted since proteolysis and reduction of the disulphide bond will release the GnRH sequence from the C-terminus of the H_(N) domain.

Reduced Sample: H_(N) Subunit Mass Theoretical Corresponding Observed Mass Mass: Structure: Mass: Difference: 49419 Da Heavy Chain + 49421 Da 2 Da Spacer + Activation Site

These data demonstrate that the GnRH ligand is attached to the fusion protein prior to activation and reduction, is attached to the fusion protein following activation in the absence of reducing agent, but is absent from the H_(N) domain following activation and reduction. This confirms that the fusion protein has correctly activated at both proteolytic sites and that the GnRH ligand is attached to the H_(N) domain through the engineered disulphide bond.

Example 7 Assessment of the Binding Ability of an LHD Protein that Incorporates a GnRH Polypeptide

The protein prepared according to Example 4 is assessed for functionality of ligand-receptor interaction using one of a number of suitable assays. For example the Gonadotrophin-releasing hormone GnRHR receptor ligand binding assays supplied by Cisbio Bioassays is a competition assay that quantifies the binding activity in a sample (http://www.htrf.com/products/gpcr/binding/ligands/inserts/C1TT1GNRH.pdf). Alternatively, a range of publicly available binding assays are reported in the scientific literature (for example Christopher E. Heise, Susan K. Sullivan and Paul D. Crowe, J Biomol Screen 2007 12: 235; DOI: 10.1177/1087057106297362). Use of such assays indicate that the GnRH TM is capable of interacting with the target receptor.

The data indicate that the GnRH TM is capable of interacting with the target receptor.

Example 8 Assessment of the In Vitro Functionality of an LHD Protein that Incorporates a GnRH Polypeptide

The protein prepared according to Example 4 is assessed for its ability to cleave SNARE proteins within the target cell. Briefly, an alpha T3-1 cell line (an immortalized gonadotroph cell line) that expresses high levels of the gonadotrophin-releasing hormone (GnRH) receptor is incubated with a compound of the invention. 24 hours later the cellular material is harvested and SNARE proteins analysed by Western blotting. The data indicate that the fusion protein comprising the GnRH TM is capable of interacting with the target receptor, leading to internalisation and cleavage of intracellular SNARE proteins.

Example 9 Creation of an LHD Protein that Incorporates a Dynorphin and a Bradykinin Polypeptide to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/D and the peptides dynorphin and bradykinin is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the dynorphin peptide. An 11 amino acid spacer is constructed between the dynorphin and bradykinin peptides incorporating a single Cys to facilitate disulphide binding to the H_(N).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/D,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/D modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 17 amino acid dynorphin peptide     -   a 11 amino acid Gly-Gly-Gly-Gly-Ser-Cys-Gly-Gly-Gly-Gly-Ser (SEQ         ID NO: 52)     -   a 9 amino acid bradykinin peptide.

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 7 and the amino acid sequence of the expression product is illustrated in SEQ ID 8.

Example 10 Creation of an LHA Protein that Incorporates a Beta-Endorphin and a Bradykinin Polypeptide to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/A and the peptides beta-endorphin and bradykinin is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the beta-endorphin peptide. An 11 amino acid spacer is constructed between the beta-endorphin and bradykinin peptides incorporating a single Cys to facilitate disulphide binding to the H_(N).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/A,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/A modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 31 amino acid beta-endorphin peptide     -   a 11 amino acid Gly-Gly-Gly-Gly-Ser-Cys-Gly-Gly-Gly-Gly-Ser (SEQ         ID NO: 52)     -   a 9 amino acid bradykinin peptide.

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 9 and the amino acid sequence of the expression product is illustrated in SEQ ID 10.

Example 11 Creation of an LHD Protein that Incorporates Two GHRH Polypeptides to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/D and two GHRH peptides is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the GHRH peptide. An 11 amino acid spacer is constructed between the two GHRH peptides incorporating a single Cys to facilitate disulphide binding to the H_(N).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 amino acid asparagine spacer (SEQ ID NO: 49),     -   the LC of BoNT/D,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/D modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 40 amino acid GHRH peptide     -   a 11 amino acid Gly-Gly-Gly-Gly-Ser-Cys-Gly-Gly-Gly-Gly-Ser (SEQ         ID NO: 52)     -   a 40 amino acid GHRH peptide.

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 11 and the amino acid sequence of the expression product is illustrated in SEQ ID 12.

Example 12 Creation of an LHD Protein that Incorporates a GnRH Polypeptide to the C-Terminus of the H_(N) Domain, Spaced by 5 Amino Acids from the Second Protease Activation Site

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/D and the 10 amino acid peptide GnRH is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the spacer to the N-terminus of the TM (GnRH).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/D,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/D modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser-Ile-Glu-Gly-Arg-Gly-Gly-Gly-Gly-Ser (SEQ         ID NO: 50) spacer incorporating an IEGR (SEQ ID NO: 33) peptide,     -   a 10 amino acid GnRH peptide modified to incorporate a Cys         residue at position 6 in place of the natural Gly (QHWSYCLRPG)         (SEQ ID NO: 51).

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 13 and the amino acid sequence of the expression product is illustrated in SEQ ID 14.

Example 13 Creation of an LHA Protein that Incorporates a Gastrin Releasing Peptide to the C-Terminus of the H_(N) Domain

The primary sequence of a chimaeric protein constructed by a genetic fusion of the LH_(N) fragment of BoNT/A and the 27 amino acid gastrin releasing peptide (GRP) is reviewed for the presence of amino acid strings that bear resemblance to the prototypical recognition site for Factor Xa (IEGR) (SEQ ID NO: 33). As no such string is found, the choice is made to use FXa as the protease to both activate the fusion protein at the LC-H_(N) junction and also to cleave the peptide bond between the H_(N) and the TM (GRP).

DNA optimised for E. coli expression is obtained commercially from Entelechon (Germany) to encode a fusion protein which has the following structure, from N- to C-terminus:

-   -   10 His N-terminal purification tag (SEQ ID NO: 48),     -   a 10 asparagine amino acid spacer (SEQ ID NO: 49),     -   the LC of BoNT/A,     -   an inter-domain linker with a primary sequence similar to the         found in BoNT/A, modified to incorporate the tetra peptide IEGR         (SEQ ID NO: 33) which is a substrate for FXa,     -   the H_(N) of BoNT/A modified to incorporate a C-terminal Cys,     -   a Gly-Gly-Gly-Gly-Ser (SEQ ID NO: 50) spacer incorporating an         IEGR (SEQ ID NO: 33) peptide sequence at the C-terminus     -   a 28 amino acid Gastrin releasing peptide modified to         incorporate a Cys residue at position 17 in place of the natural         Arg and an additional Gly residue at the C-terminus to replace         the need for C-terminal amidation (VPLPAGGGTVLTKMYPCGNHWAVGHLMG)         (SEQ ID NO: 54).

E. coli codon usage was assessed by reference to software programs such as Graphical Codon Usage Analyser (Geneart), and the % GC content and codon usage ratio assessed by reference to published codon usage tables (for example GenBank Release 143, Sep. 13, 2004) to ensure that the construction does not result in poor codon utilisation. The DNA was incorporated into a standard cloning vector, for example pCR4, prior to transformation into E. coli host. The integrity of the ORF DNA was checked by sequencing. The final ORF is illustrated as SEQ ID 15 and the amino acid sequence of the expression product is illustrated in SEQ ID 16.

Example 14 Method of Treating Patients Suffering from Prostate Cancer

A 56 year old male is suffering from prostate cancer advances to a situation in which androgen-deprivation therapy is no longer sufficient to control the disease. The man is treated by local administration of a composition comprising a TSI of the present invention (in this specific example, a GnRH peptide TM based TSI) into the vicinity of the prostate. The patient's condition is monitored and about 2 months after treatment the physician notes a decrease in tumour size indicating successful treatment with the composition comprising a molecule of the invention.

Example 15 Method of Treating Patients Suffering from Neurogenic Inflammation

A 62 year old female diagnosed with rheumatoid arthritis complains of joint stiffness and swelling. A physician determines that the joint stiffness and swelling is due to chronic neurogenic inflammation. The woman is treated by local administration of a composition comprising a TSI of the present invention (in this example, the TSI comprises an opioid TM—parallel examples are run with TSIs comprising nociceptin or dynorphin TMs) in the vicinity of the affected area. The patient's condition is monitored and after about 1-3 days after treatment the woman indicates there is reduced joint stiffness and swelling. At one and three month check-ups, the woman indicates that she continues to have reduced joint stiffness and swelling in the area treated. This reduction in chronic neurogenic inflammation symptoms indicates successful treatment with the composition comprising a molecule of the invention.

Example 16 Method of Treating Patients Suffering from Endometriosis

A 39 year old female presents with pelvic pain due to endometriosis that is not adequately treated with nonsteroidal anti-inflammatory drugs (NSAIDS) and combined estrogen-progestin contraceptives. The physician administers a composition comprising a TSI of the present invention (in this example, the TSI comprises an opioid TM—parallel examples are run with TSIs comprising nociceptin or dynorphin TMs). The patient's condition is monitored and after about 1-3 days after treatment the woman indicates there is reduced pain. At one and three month check-ups, the woman indicates that she continues to have reduced pain and has enhanced freedom of movement. This reduction in symptoms associated with endometriosis indicates successful treatment with the composition comprising a molecule of the invention.

Example 17 Method of Treating Patients Suffering from Overactive Bladder

A 58 year old male complains of increased urinary urgency. A physician diagnosis the patient with overactive bladder having a neurological component involving abnormal neuron activity. The man is treated by injecting urethroscopically a composition comprising a TSI of the present invention (in this example, the TSI comprises an opioid TM—parallel examples are run with TSIs comprising nociceptin or dynorphin TMs). Depending on the location of abnormal neuron activity, the toxin can be administered into e.g., the detrusor, the bladder neck including the external and internal urethral sphincters, the trigone, the bladder dome or other areas of the bladder wall, and/or other areas surrounding the bladder, such as the urethra, ureter, urogenital diaphragm, lower pelvic muscles, prostate, bulbourethral gland, bulb, crus or penis. The patient's condition is monitored and after about 1-3 days from treatment, and the man indicates that he has a reduced urgency to urinate. At one and three month check-ups, the man indicates that he continues to have a reduced urgency to urinate. This reduction in an overactive bladder symptom indicates successful treatment with the composition comprising a molecule of the invention.

Example 18 Method of Treating Patients Suffering from Neurogenic Inflammation

A 62 year old female diagnosed with rheumatoid arthritis complains of joint stiffness and swelling. A physician determines that the joint stiffness and swelling is due to chronic neurogenic inflammation. The woman is treated by local administration a composition comprising a TSI of the present invention in the vicinity of the affected area (in this example, the TSI comprises an opioid TM—parallel examples are run with TSIs comprising nociceptin or dynorphin TMs). The patient's condition is monitored and after about 1-3 days after treatment, and the woman indicates there is reduced joint stiffness and swelling. At one and three month check-ups, the woman indicates that she continues to have reduced joint stiffness and swelling in the area treated. This reduction in chronic neurogenic inflammation symptoms indicates successful treatment with the composition comprising a molecule of the invention. A similar type of local administration of a protein as disclosed in the present specification can be used to treat a patient suffering from chronic neurogenic inflammation associated with any monoarthritis, oligoarthritis, or polyarthritis, such as, e.g., osteoarthritis, juvenile idiopathic arthritis, septic arthritis, a spondyloarthropathy (including ankylosing spondylitis, reactive arthritis (Reiter's syndrome), psoriatic arthritis, enteropathic arthritis associated with inflammatory bowel disease, Whipple disease or Behcet disease), a synovitis, gout, pseudogout, or Still's disease, as well as, a bursitis, a rheumatic fever, or a tenosynovitis. In addition, systemic administration could also be used to administer a composition comprising a molecule of the invention to treat chronic neurogenic inflammation. 

The invention claimed is:
 1. A nucleic acid encoding a single-chain polypeptide fusion protein comprising: (a) a non-cytotoxic protease capable of cleaving a protein of the exocytic fusion apparatus of a target cell; (b) a targeting moiety capable of binding to a binding site on the target cell, which binding site is capable of undergoing endocytosis and being incorporated into an endosome within the target cell; (c) a translocation domain capable of translocating the protease from within an endosome, across the endosomal membrane, and into the cytosol of the target cell; (d) a first cleavage site that is cleavable by a protease, wherein the first cleavage site is located between the non-cytotoxic protease and the translocation domain; and (e) a second cleavage site that is cleavable by a protease, wherein the second cleavage site is located between the translocation domain and the targeting moiety and is not a destructive cleavage site; wherein the targeting moiety and the translocation domain are capable of forming a covalent linkage such that, following proteolytic cleavage at the second cleavage site, the targeting moiety remains linked to the translocation domain by the covalent linkage.
 2. The nucleic acid of claim 1, wherein the translocation domain of the fusion protein is located between the non-cytotoxic protease and the targeting moiety.
 3. The nucleic acid of claim 1, wherein the non-cytotoxic protease of the fusion protein is located at the N-terminus of the protein.
 4. The nucleic acid of claim 1, wherein the covalent linkage of the fusion protein is a disulfide linkage.
 5. The nucleic acid of claim 1, wherein a short polypeptide that provides a secondary polypeptide structure is located between the translocation domain of the fusion protein and the targeting moiety, and wherein the secondary polypeptide structure acts to bring part of the targeting moiety into close proximity to the translocation domain, thereby making formation of the covalent linkage energetically more favorable.
 6. The nucleic acid of claim 1, wherein the targeting moiety of the fusion protein comprises first and second domains, and wherein the first and second domains are separated by at most 10 amino acid residues.
 7. The nucleic acid of claim 6, wherein the first and second domains of the targeting moiety are derived from ligands to different receptors.
 8. The nucleic acid of claim 1, wherein, following cleavage of the fusion protein at the first and second cleavage sites, the targeting moiety of the fusion protein is capable of interacting with the binding site on the target cell (i) via an interaction between an N-terminal domain of the targeting moiety and a domain of the binding site, and, simultaneously, (ii) via an interaction between a C-terminal domain of the targeting moiety and a domain of the binding site.
 9. The nucleic acid of claim 1, wherein the targeting moiety of the fusion protein comprises a peptide selected from the group consisting of: a gonadotropin-releasing hormone (GnRH) peptide, an opioid peptide, a beta-endorphin peptide, a bradykinin peptide, a BAM peptide, a nociceptin peptide, a dynorphin peptide, a galanin peptide, an enkephalin peptide, a substance P peptide, a corticotropin-releasing factor (CRF) peptide, a gastrin-releasing peptide (GRP), a Neuromedin B peptide, a bombesin peptide, a gastrin peptide, a CCK peptide, a somatostatin (SST) peptide, a cortistatin (CST) peptide, a growth hormone releasing hormone (GHRH) peptide, a PAR peptide, a parathyroid hormone (PTH) peptide, a vasointestinal peptide (VIP), a beta2 adrenoreceptor agonist peptide, a gastrin-releasing peptide, a calcitonin gene related peptide, a thyroid stimulating hormone (TSH) peptide, an insulin peptide, an insulin-like growth factor peptide, a gonadorelin peptide, a corticotrophin releasing hormone (CRH) peptide, an adrenocorticotropic hormone (ACTH) peptide, and a pituitary adenyl cyclase activating peptide (PACAP).
 10. The nucleic acid of claim 1, wherein the non-cytotoxic protease of the fusion protein and the first cleavage site are separated by at most 10 amino acid residues.
 11. The nucleic acid of claim 1, wherein the translocation domain of the fusion protein and the first cleavage site are separated by at most 10 amino acid residues.
 12. The nucleic acid of claim 1, wherein the translocation domain of the fusion protein and the second cleavage site are separated by at most 10 amino acid residues.
 13. The nucleic acid of claim 1, wherein the targeting moiety of the fusion protein and the second cleavage site are separated by at most 10 amino acid residues.
 14. The nucleic acid of claim 1, wherein the first and second cleavage sites are capable of being cleaved by the same protease.
 15. The nucleic acid of claim 1, wherein the non-cytotoxic protease of the fusion protein is a clostridial neurotoxin L-chain or a fragment thereof.
 16. The nucleic acid of claim 1, wherein the translocation domain of the fusion protein is a clostridial neurotoxin H_(N) domain or a fragment thereof.
 17. The nucleic acid of claim 1, wherein the fusion protein encoded by the nucleic acid comprises a purification tag.
 18. A DNA vector comprising a promoter, the nucleic acid sequence of claim 1, and a terminator, wherein the nucleic acid sequence is located downstream of the promoter and the terminator is located downstream of the nucleic acid sequence.
 19. The complementary DNA strand of the nucleic acid of claim
 1. 